As long as tools to unclip the shell aren't consider specialized, I think almost all existing handhelds are gonna meet the actual requirements here - they just have to be user replaceable, not use swappable, without the use of specialized tools or thermal energy. If you can unscrew it, disconnect the old battery and connect the new one, it complies. It's really only an issue in waterproof devices, where they have to glue everything to seal it.
I read a lot of people claiming that waterproofing technology has come to a point where this isn't too much of an issue, but that's as far as my knowledge goes
It's true. If you put a little gasket around the edges and make sure it's held down tightly (clips, screws etc) it's fine. Glue is cheaper and faster to manufacture, that's why companies claim it's necessary
I think the specialized tools thing leaves a lot of room for interpretation. For instance, Nintendo consoles likes to use triwing screws. A triwing screwdriver is a standard tool technically, but they aren't found at most hardware stores. I could see the argument that a triwing screw would not comply.