+1 on Thunder’s advice. Complete, dedicated 22lr ARs are likely the best option right now. I decided to go the conversion kit route a year back, but I suppose that is likely just as hard to find at the moment, and not as accurate as a purpose built 22lr AR.
I have noticed that hole in the wall gun shops, or less-visited Academys/Dicks usually have one or two 22lr ARs on their shelves at any given time (NE Texas/N Louisiana area). It may be worthwhile to spend a Saturday gun shop hopping. I’ve seen plenty of S&W M&P 15-22s on shelves lately. Take advantage of the fact that most people only shop online these days. Go take a look around and you will probably find something to fit the bill.