From my research, an M4 SBR (~11.5”) with a can seems an optimal compromise.
You can keep the noise reducer, and I’m running mine as a CMMG ‘dialable’ piston set up. Had to remove a whole loop from the buffer tube spring, but it runs like a sewing machine now. But for one-handed shooting, the Bushmaster 5.56 pistol in carbon fiber is the cat’s meow.