The problem I have with rings in any public pool is that if a child goes under and one is over him/her then the lifeguard or parent can't see the child. Children have drown this way. More likey when there a few bunched up, I guess. I know that in pools I have had to move them so my kid when swimming underwater could come up for air. They worry me. Our community pool doesn't allow rings or floats of any type for that reason. They are great fun in a Lazy River, but have you noticed that most require that you stay in the ring. Same reason.
As far as the arm rings...I wouldn't imagine those being off limits. But, I suggest a swimming vest. A life jacket works, but there are better alternatives. We used one for my oldest that allowed you to take out the floaty wafers one at time so they eventually started to swim on their own. My younger son used a Speedo vest. It seemed quite comfortable much more than a life jacket. He loved it and I know of a lot of kids who use them. I know our Target sells them for around $20. Still, even with a vest keep an eye on those kids.