Yeah the pressure of the rifle round is much much higher than that of a pistol round. It would most likely blow up your 9mm suppressor. Unless it's a older all steel foot long 9mm suppressor, then maybe it could handle it, but still wouldn't recommend it. I would get a proper rifle can for it.
You can shoot a 9mm through a 45acp suppressor because both the size of the bullet is smaller and the pressure is lower. You can shoot a 5.56mm round through a 7.62mm suppressor because again the bullet is smaller and the pressure is lower. You can shoot a subsonic 300BLK round through a 9mm suppressor, smaller bullet, around the same pressure. You can't shoot a supersonic 300BLK through a 9mm suppressor because the pressure is just too great.
You have to take these things into consideration. Both the size of the bullet and the amount of pressure the suppressor can handle.
I would probably recommend going with a pistol type with Sig brace if a SBR is a no go. That way it's still pretty much a SBR, short barrel and sort of a stock, but no NFA paperwork. Maybe a Mp5 pistol clone with Sig brace stock. Or maybe go with an AR-15 pistol with Sig brace stock in 300BLK and only shoot subsonic ammo through it.