This is great. I have the Fairphone 4, which does have a couple of issues, but the fact that the battery can be replaced will increase the usable lifespan of the phone.
I have a Pixel 2 used for messing about with Lineage, but the battery only lasts fifteen minutes, but is otherwise still a great phone. If it was easy enough to swap out that battery, I'd probably still be using it as my main.
It typically does impact waterproofing, but the majority of use cases won't encounter an issue.
In saying that, though, the Fairphone 4 has pulled off an IP54 rating, so there's still hope!