I started using the desktop (electron) version on macos and when I click on the "save to browser" button, the game is indeed saved but impossible to know where the file is.
I need to know where the file is for versioning or just even cleaning purposes (also I was trying to access the same saved game from different accounts and it did not work so it would help to know where the file is in a lot of situations)

There are no file _per se_, the save is located in the localstorage of the embedded electron browser and is not accessible. The only way to have a "save file" is to "export a playable", save it to disk, and then load it again. The playable file contains everything (all the tiles, all the rooms, the source ink and the compiled ink). This playable file should be versionnable easily (the bipsi json and the ink script are both saved with correct line formatting, so that git can diff it correctly)