How do I recover Joplin notes if they were never exported?

I have an old Ubuntu machine that no longer works, but I can still access its drive through a live USB. None of the notes were ever exported; though, I was expecting to recover them by some other means. How do I do this? I see the Joplin app folder/files and that it was installed on the machine via snap.

Those are stored in an SQLite database. Default location (normal and snap):

~/.config/joplin-desktop/database.sqlite
~/snap/joplin-desktop/current/.config/joplin-desktop

Find the one you are after on your system and then from command line you can do ...

sqlite3 ~/.config/joplin-desktop/database.sqlite
sqlite3 ~/snap/joplin-desktop/current/.config/joplin-desktop

and then use the SQL language to view and dump data from it. .help will show available options.