I want a lightweight hunting chassis for a Ruger American Ranch, but I'm overly picky and want one with an integral folding stock instead of an AR buffer tube mount. I don't really want to use a folding adapter with a buffer tube, I'd rather just find something like the Sig Cross style chassis.

I am flexible on mag options, but it's the 7.62x39 so if I could keep the Mini 30 mags (I have several), it would help. That's not a dealbreaker though.

Does such a thing exist? Or am I stuck with AR buffer tube stock options because everyone is obsessed with making bolt guns compatible with AR buffer tubes?

I looked a couple of years ago, and didn’t find any.

I did find some custom made (one off) folders for different rifles.  You may need to go that route if you really want a folder for the RAR.

MDT has the only folding option I am aware of and it uses AR buffer tube.

You will have to give up the MIni 30 mags to convert to any other stock.