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It's official: Smartphones will need to have replaceable batteries by 2027
(www.androidauthority.com)
This is a most excellent place for technology news and articles.
I don't think an actual waterproof phone even exists. They're water resistant.
My Samsung Galaxy XCover 6Pro has a removable battery (and a headphone jack) and it's ip68 rated. You wouldn't be able to tell from the outside that the back cover comes off.