Spot on. Anything based on the AR-18 design, which begat the AR-180 semi auto civilian version (which was promptly banned), gets rid of the buffer tube function on the AR-15 to balance the BCG. It uses the dual captive recoil springs, a design that migrated to a bunch of other modern firearms.

I’ve been interested in the Aly & Kaufman AKB-23, basically a L85/SA80 replica lower that you throw a BRN-180 on and add some furniture to complete the look. So short version, yeah I think you could whittle a wooden lower for AR-18 style uppers. Probably only get a few shots off before it cracked though, wood can be quite brittle like that.