I think the biggest concern with the floating flooring in bathrooms and kitchens is that much of it is engineered flooring. This stuff just doesn't do well when wet. But, the plastic underlining is for water seeping up from the bottom. This generally isn't a problem in a bathroom/kitchen moreso than water from the TOP (i.e. spills, splashes, wet feet, etc). I've seen people use it anyone. Especially in kitchens. Here's what you want to do to help.

Get rugs for the bathroom floor. Try to find ones that have a water proof lining underneath. This will mean they'll be a bit harder to wash and dry, but, it'll also mean that your floor wont get wet. Leave the door open or a vent fan or a window open when showering. This will keep the humidity down. Additionally, if you don't have a vent fan, buy a small rotating desk fan and put it out to blow on the floor for an hour or so after every shower.

For the kitchen, get waterproof rugs for all the wet areas: in front of the sink, in front of the dishwasher, in front of the fridge, in front of common food prep areas. You'll have to do a but more washing when food drops on a rug vs your floor, but, it'll keep the moisture off the floor.

The kitchen is less of a big deal than the bathroom.

There may be some kind of sealant that you can buy. I'm not sure.