A 9mm can offers much more versatility than a .22 can. The same applies to a 7.62 suppressor versus a 5.56 can. If you're able, I'd try to listen to a couple of cans before you commit to purchasing one that you'll probably own for a long, long time. (There's little resale value on a used can versus new cost.) Honestly I can't hear much difference between a dedicated .22 can versus a 9mm can or 5.56 ammo shot through a 7.62 can. You loose very little to suppression and increase the number of applications/host guns available to use with a single can. The increased bore size doesn't seem to matter when you increase the can's volume and volume is your friend when it comes to suppression.
In any case, if you go with a 9mm can for .22LR use, make certain you buy one that can be disassembled for cleaning. .22 rimfire is probably the nastiest, dirtiest round ever produced. I'm unaware of any .22 ammo that's jacketed... it's all copper washed or copper plated and there's a huge difference. Over time, .22LR ammo will leave lead deposits inside you can, especially in the area of the blast baffle. I've leaded up my 9mm suppressor so badly it was laughable. My .22 use in a 9mm is primarily with full auto use so the leading is accelerated. Just understand that leading is a fact of life with all .22 rimfire cans.
If you decide to buy a dedicated .22 can, make certain it's one that you can take down for cleaning. Most of today's .22 and 9mm cans do disassemble for cleaning but not all of them. I'm not aware of any centerfire rifle can currently in production that disassembles for cleaning so any rimfire use in one of those should be very, very limited.