I’d expect frozen pineapple to be quite good even after thawing. It has a lot of long fiber for structure that I’d expect would survive.

Frozen and thawed watermelon (and other similar melons) would likely be dreadful.

It’s good, but it’s not fresh either. It’s better than canned pineapple

I think it depends on the application, in a situation or recipe where fresh fruit is important (like a tart), frozen fruits likely won’t measure up. In something baked (like a pie) frozen can work well. A smoothie, frozen fruits can be amazing.

Not awful at all. Actually makes for a great summer popsicle.