As a background, I have an older HT set up that I purchase around 2008-2010.  

TV:  Samsung Samsung LN46A650
Receiver:  Denon 3808ci
Speakers:  Energy RC70, RC LCR, RC Micro (rear surround), HSU sub (I don't use as I live in duplex with 90+ old neighbor)
Blu-ray/DVD/Streaming device:  Sony PS3

Was using Xfinity through Comcast which allowed me to use their apps for streaming stuff.  I am switching to T-Mobile limited 5g internet because of price.  Comcast would never just give me internet service for $70-80/month.  Always had to have some sort of bundle which I didn't want.  They've slowly raised the price from $107/month to $128/month.  So, I'm ditching them.

Saying that, my T-Mobile receiver is upstairs so I can receive best signal.  All equipment is downstairs.  Currently using three remotes now--one for PS3, one for receiver, and one for TV.  I'd like to get something that streams movies that I could use one remote for everything (if possible).

I am not a technical Guru.  I would like it if a streaming device was able to decode audio and pass through to my receiver/amp.  But, I could do with something that would provide good audio.  

It's been so long since I purchased everything, that I cannot recall exactly how I set up the PS3. I recall, at the time, it was the best thing to purchase--can't recall if I used it to decode Blu-ray audio to pass through receiver, and used the TV processor for video.  It was something like that.  I don't watch TV/Movies too often--maybe a two hours/week on the weekend.  Also, I'm fairly poor right now due  to inflation; saying that, I don't want to spend a ton upgrading my equipment. I don't know if TVs use different mounting hardware today vs 2008. I've thought about upgrading the TV (those aren't too expensive).  But, I like my old stand, and  I don't know if the old mounting hardware would work on newer TVs.

Well, looks like the Sony UBP-X700 open box from Best Buy for $102 seems like a good buy.

Somebody mentioned Apple TV...that seems like a good choice as well.

I am not sure what you are exactly looking for.  I am building a deck sound system.  My goal is to put the amp into a storage room and route the speaker wires through the wall.  That said, I don't want to have to go into the storage room to control it.  Likewise - wiring from the living room would be a nightmare - and I am pretty sure I would not have bluetooth access from the deck.  The solution I am going to try is a WiiM streamer (there are lots of streamers out there - this is currently one of the most popular on some audio forums.  It can connect to the internet via WiFi (the pro version also has ethernet.  It can connect to other devices via WiFi or Bluetooth.  It has analog (with volume control) out, and 2 different forms of digital out (if you only want a connect to a more complicated audio system.  It is controlled by an apps, optional Bluetooth remote, or be part of an Alexa system).

It is very much like a Roku, Apple TV, or Fire stick - but for Audio only - and can deal with lossless streams (high bit-rate, no compression).  It is directly compatible directly with most of the streaming services, plus it has Bluetooth, Airplay, and I think the Android Equivalent (but I think the general goal is to let it do the heavy lifting and only use the phone as a remote-but I think you can get better bit-rate without compression if you let it do the streaming itself).
---
Of course there are a lot of integrated devices that can do this as well - so for most people this would just be an economic way to stream to their existing stereo without upgrading major components.  I doubt many people are trying to connect it directly to an amp.  It can also connect directly to powered Bluetooth speakers.

Or at least that is everything I think I read about it.  It is on my desk, but it is the first part of the entire sound system to come in.
---
There are arguments online if it is bit perfect (most argue that testing showed it was).  Biggest weakness is it has a so/so DAC.  I would consider putting on an external DAC, but it would completely defeat my intended use (would loose remote volume control).  At the end of the day, it will be a fairly cheap front end of a $1k stereo system for me.

Neither am I
That's what I'm trying to figure out, I guess.

I had Xfinity.  I only wanted internet.  I use streaming services--cable TV is horrendous.  But, I could use Xfinity's apps for Netflix, Amazon, etc.  And, I had a wired connection from my router.  I recently switched to T-Mobile 5g (limited) internet.  The modem (or whatever the thing is that receives signal and acts as wireless router) is upstairs.  So, no wired connection.  My equipment is old--at least 15 year old tech.  Currently using PS3 to stream stuff and want to try something better.  I don't know the tech, but I would imagine some things provide better picture/sound than others.  And, some provide more/better options.

I am rather poor right now due to inflation regressing my purchasing power by about eleven years.  So, I'm not looking to upgrade my receiver and TV any time soon.  Maybe the TV as I can likely get a $400 TV that is as good or better than my $1,400 TV from 2008.  Regardless, anything I would do would be piecemeal.  And, higher resolution stuff (i.e. 4k capable TVs and receivers) probably wouldn't work anyway via streaming as my internet connection speed isn't very fast (75mbps and under).

Again, looking for ideas for a good streaming device.  I thought of Blu-ray w/streaming as it would be a 2 in 1.  However, somebody mentioned Apple TV, and that seems to be a nice device.  If I wanted to watch Blu ray, I still have the PS3.  One problem with the PS3 is it doesn't work with remotes without an adapter.  The benefit of a new device would be I could likely program one remote to use for everything.

I like Roku - its a 4K compatible stream box that can run any app you want (ie Netflix, Sling, Amazon Prime, Hulu TV etc.) for TV/Movies and any other App (ie Pandora, Spotify, Amazon Music, etc. etc.) for music.

It connects to your AV receiver (or sound bar) via HDMI.

Plus one on Roku. So far i never had any technical problems with it and we are using for 3 years in total now.
If you want to have few different options, try to reach arvig customer support on their website .
I know a lot of people are also using firestick, but honestly i have no idea what is the difference with the roku and what is better.

If you want to minimize remotes, then probably best to use a smart TV's built in streaming apps, get an eArc compatible AV receiver and TV. That way your TV remote will control everything.

I was coming to say this. Sell your current TV, and get the best current TV you can afford. The TV is the streaming device nowadays.
The receiver then will just handle sending out the audio (but maybe not the most current audio formats ie Atmos, etc) from the the TV. Then just keep the PS3 for physical DVD/Blurays.