Change Bash shell

I recently received a Steam Deck and I love it!

I also planning to use it for development. On my PC I get used to Fish shell and usually use it instead of Bash. I can install it on Steam Deck and set it to the default shell, but after a system update it will be wiped. I can create a script and run it after each update, will I be able to login if my user points to `/usr/bin/fish` that doesn't exist in the system?..