It makes sense to use the ACR stock. It folds, has LOP adjustment and two-position cheek rest. All you need to do is figure out the mating hinge and adapter for the gun you want to mount it on.
Dan Haga has a number of designs for the ACR stock. He makes an adapter that replaces the buttpad/stock portion of the ACR stock and allows you to mount a Tailhook brace on the end.
In lieu of the recent news of ATF taking another look at firearms with braces, F5 MFG is coming out with an ACR brace to convert an ACR stock into a brace. F5 MFG is known for their soda can launcher. While it is not the XS Products can launcher, it is a similar product. I actually bought one last year in Vegas from Ventura Munitions while I was in town for SHOT Show 2019.
The ACR stock has become a rather popular stock alternative for various firearms. One of the earliest uses I can recall is KDG and their ACR stock with an adapter for the SCAR platform. Other companies have used the ACR stock on their guns as well.
The problem with the Dan Haga designed options is that it requires a third party brace. Well now F5 MFG is skipping the middle man and made their own ACR brace for their MSS (Modular Stock System).
You can also order a complete brace setup for $399. F5 makes four versions of their ACR Brace for MP5, CZ Scorpion, B&T APC9, as well as the Grand Power Stribog.