All hail the overseerr

You welcome. The more you make mistakes the more you learn, just remember backups backups backups and you should be fine.

When you say “I told it to sync my one drive folder, and it did it’s best” did you install nextcloud desktop and point it at the same folder that was currently syncing onedrive?

If yes, never do this. You should never layer two sync services that support virtual files over the same folder. The best way migrate to nextcloud is to use the nextcloud apps that connect to one drive and help you migrate.

Failing that the correct way would be to either set onedrive and nextcloud to sync 2 Seperate folders then copy from the onedrive folder to the nextcloud folder. Or set one drive to download all files, disable it entirely, then install nextcloud syncing with the formerly one drive folder.

Honestly these things are really vital to learn if you want to be self hosting, however if you’re unfamiliar with them I would not start with your password vault. You’re almost certainly going to make mistakes and risk losing the vault. I would learn on something less vital then once you’re feeling more comfortable add vault warden.