They should be in local storage of your browser
That's good to know, but... when I launch the game via the itch app, it neither uses Opera GX nor Firefox to play the game. It seems to be some integrated browser. And I have zero clue where that one has its local storage
Well, itch is a 3rd party company I have no affiliation with whatsoever. So, you might want to ask on their forums or try googling it.
A quick search resulted in this:
windows: %APPDATA%\itch\localStorage
mac: ~/Library/Application Support/itch/localStorageI've no idea if it's true cause I don't have the app.