1000% don't actually know what I'm talking about, but I'm also working on a bath project (my first) and passing along what my research has revealed. Please do downvote if you know better.
I've seen a few recommendations that with a floating floor, you should definitely leave an expansion gap (your flooring will tell you exactly how much, mine says 3/8 inch) between the tub/shower and the flooring and that you should NOT fill that gap with caulk. The consensus recommendation I found was that you should adhere a waterproof quarter round directly to the bath/shower and caulk that, which allows the flooring to expand underneath.