Hi Dayne and welcome. Yes, you can add a CVA Picatinny/Buffer Tube Adapter and then add a folding Picatinny Brace. A Folding Stock would require an NFA Registration and $200 Tax Stamp. https://farrow.tech/cva-picatinny-buffer-tube-adapter/ ------------------------------- budsgunshop.com/search.php/q/picatinny+folding+brace ----- Cheers and stay safe!

Good evening to you!! A stock on a pistol changes it's description. It becomes a snr which requires registration and tax stamp. Your best bet is to add a pistol brace such as any shown in the below link. Hope this helps. Have a good rest of your day.
budsgunshop.com/search.php/q/picatinny+folding+brace