You're proving the point.

1) iPhones for example are ip68 rated while those are just ipx8/9

2) Do you want to be limited to the universe of those search results? Do you want to buy a Sony Xperia?

You can't make batteries directly replaceable at the same quality and price. There are tradeoffs. Obviously waterproof non-embedded batteries exist. Just like you could make a removable battery the same slimness as embedded. With massive tradeoffs. It's capacity will be terrible. No one is surprised a removable battery can be waterproof but the point is there are tradeoffs.

No, the list was "Cheaper, higher battery capacity, water proof, smaller, stronger". I don't think it's all that controversial to say that there are engineering tradeoffs to be made here. You can make a waterproof phone with a removable battery, but you can't make a waterproof phone with a removable battery that is as good or better than an iPhone in every other respect too. If you could, iPhones would already have removable batteries.

Oh yes, the famous Galaxy XCover 7 Pro. People are camping out in the rain waiting for their release because replaceable batteries are under such high demand.

Not water proof and definitely big for its capacity.