I am not sure if there are chair rentals, maybe closer to the pier (which was closed as of last week per my sister that lives there). I know there is some loud music at different bars/restaurants also in that area on the beach. We just walked thru it because we were walking.
My sister lives in FM and we go every April, well minus 2020. We haven’t gone to FMB in a few years though because it’s not a favorite. The water isn‘t as clear as other areas, almost brown at times (this changes with the tides and maybe seasonally or when they release water from lake O). But the sand is the softest whitest sand ever! Lots of sand dollars in the water near the pier and lots of Augers (shells) up at the north tip/park up there.
On Sanibel there are a few public beaches but they don’t have rentals-Bowmans is the largest. Then there is the lighthouse (nice for shelling depending on the tides), another beach in between, maybe starts with an A....just came to me Algiers. Then at the bridge between Sanibel and Captiva there is a public beach on either side but small lots so difficult to get a spot. And just past the Bubible room there is the other public beach on captiva, also a small lot. Lots of coral there.
The state parks have chair rentals. I can’t recall if it’s one or both have rentals-lovers Key I am pretty sure has chairs and umbrellas, not sure if it’s at both end points or just the one you take the tram to-we have had my mom with dementia and a bad hip so walking the shorter path doesn’t happen with her. But I don’t think Barefoot does-that is probably my favorite in the area, just driving in and looking at the houses, wowzers! I know the small public beach in Bonita doesn’t have chairs but it’s a short walk and they do have a bathroom.
if you wanted to take about a 90 min drive north, I highly recommend it. Go to Manasota key beach. It is free parking (unlike all the above) and pick sharks teeth. When the tide goes out it’s just loaded. But we dig in the water too. This picture was just from “shark tooth beach” aka ManasoTA key Beach.
Enjoy your time. It is a beautiful area although it’s getting more and more crowded each time we go.