I have heard multiple gun store employees tell me different things and read news articles that contradict one another so I really want to know from somebody that has knowledge about this, is it legal to build myself an ar pistol?

Home builders must apply to CADOJ for permission and a serial number iirc, beforehand. Other than that it's OK.

Negative. Safe handgun roster, you won't get approved. If built before 2014 SSE and registered through CFARS (last year?) then it's grandfathered in. Well sort of. There was that whole CADOJ coming door to door confiscating legally made home built AR pistols but I think they realized where they were heading and stopped that pretty quick.

There's a single shot AR pistol I think made by Franklin Armory that was approved.

And also intrastate interfamilial AR pistol transfers.

Other than that no you wont get one here.

True, the State of CA will not let you DROS a new, semi auto AR style pistol anymore. Or, build your own lower. However:

Franklin armory has a single shot AR pistol on the approved DOJ Safe handgun roster.  It is a complete pistol, but with no gas block or gas tube on the barrel. So, "Bolt action" basically.

Also, Titan Arms sells a single shot pistol.

Why the heck would I want a single shot pistol!? you ask..  Well, it gets you a legal AR style pistol in California for starters. Yep, a fun, customizable, "Legos-for-adults" "interchangeable/add additional parts" AR style pistol.

https://franklinarmory.com/products/restricted-state-products/california-approved-pistols/

https://titanballistics.com/titan-firearms/invictus-small-frame-ar/rifles/pistols/

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if you are able to acquire a lower that has been DROS'd as a "pistol" yes. Even then, IIRC, it has to be built first as a single shot and then converted to semi with a fixed 10-round magazine.

DOJ was threatening people that bought the franklin armory gun then converted to semi. calling that "manufacturing" a non roster handgun.

storing the upper removed from the lower when not actively shooting might be a good idea in California.

Note that it would have to be a complete gun, not just a lower or they might come after you for manufacturing an off roster pistol.  The single shot stuff was done away with years ago for off roster guns being converted back to semi auto.  I had to consult with a lawyer on this topic and the consensus was that it wasnt something he would recommend doing.

ETA if it was complete then it would now be an assault weapon too and you couldnt transfer it to begin with.

I wouldn't want to be the test case. But assembly is not manufacturing. I'm unaware of anyone being prosecuted for "manufacturing" by altering the function of a factory lower/frame to semi automatic. Now an 80% lower, thats manufacturing.

Not if it has a fixed 10-round magazine.

Easiest way to go about this w/o any gray area is buy one from a private party and make sure that it say's "Pistol" and "Semi-Auto" on the DROS. Not all FFL's will do this but some will like Ammo Bros or RifleGear.