You say that like it'd be a simple process to accommodate the different thicknesses of battery..
This is already a thing for some [dedicated] cameras like the Canon EOS series.
This is a solved problem and not an issue.
It's kind of comical how accurate this comment is https://news.ycombinator.com/item?id=48807174
[1] https://www.gsmarena.com/samsung_galaxy_xcover7-12784.php
[1] https://www.phonearena.com/news/Extended-battery-with-kick-s...