The reason a 12 gauge suppressor is possible is because the shot is contained in a shot cup, a plastic sleeve that holds the shot together until it leaves the muzzle and is no longer supported (held closed) by the bore.
Silencers made for shotguns have some rails or bars inside them to press against the shot cup and keep it closed, holding the shot charge together, even as the hot gasses behind the wad and shot cup will pass in between those rods and enter the volume of the can itself.
.22 rimfire shotshells have no such shot cup or wad.
The blue plastic capsule on a CCI rat / snake shotshell is made to shatter, and I don't think it will keep the shot payload intact as it flies thru a can.
The Salvo 12 works by having rails that contain the wad in the can. As was said, unless you can make your own and experiment, I wouldn't risk the endcap strike or damage to your baffles.
So Nonliberal
says it seems to work with a 4 inch can. What about some of the modular 22 cans that can be shortened below 4 inches? Maybe not as quite as quiet, but seems like maybe would work?