Fairphone exists. The batteries are easily replaceable, they have a video on their website. It's no thicker than many other phones, runs on non Google OS, maybe just check it out. I have one and am totally satisfied with it.
I support changeable batteries as a 'no duh' feature. But when I checked out Fairphone previously (several years ago when I was phone shopping) and personally found it as 'neat concept, but a shame it seems to have been born obsolete' and lacked some of the hardware features I was looking for.
If it works for you, great though.