Where are the wine prefixes stored in linux? And Is it possible to choose where the prefixes are stored such as on a internal SSD?
Default prefix location is in:
Some install scripts install a custom version of wine. These are usually placed in the game directory under ./prefix.
The prefix to use can be configured in the Lutris game options where the path to this prefix can be entered. This makes it possible to make custom wine builds and use them in Lutris.
I have everything which has to do with gaming outside of my home directory so I made a symbolic link in my ~/.local/share directory named lutris and pointed to a directory elsewhere. Here I moved all Lutris related stuff.
TL;DR: You can place prefixes anywhere.