I have ridden on sidewalks in FL myself, specifically Old Scenic 98 along the coast at Mirarmar Beach. The "sidewalk" is more like a MUP alongside the road, used by lots of joggers and folks riding slowly on rented bikes. But for me that sidewalk was the WORST PLACE EVER to ride! Every hundred yards you had driveways with cars turning in or pulling out, and invariably they were looking at the road and NOT looking at what was coming from either direction on the sidewalk. Very, very dangerous. The driveways and street crossings USED to have painted crosswalks, but those have been removed and the painted STOP line is now placed AFTER the sidewalk, up at the edge of the main road. Absolutely ludicrous.
My problem with most of the OP's posts is that he incorrectly ASSumes that all road cyclists are paying no attention whatsoever to their surroundings. He ASSumes that because a cyclist is taking the lane that he MUST be oblivious. Simply not the case. I take the lane most of the time on multi-lane roads, and usually ride in the right tire track on 2-lane roads. But I use a helmet mirror, and never use earbuds, and also use very bright lights, high-vis, and reflective gear. I make myself as conspicuous and visible as possible, and am always aware of what's happening around me at all times.
THAT is how you stay safe on the roads, NOT by cowering off to the side.