The export JSON includes followed_communities and blocked_communities among other details.

I’ve never tried doing an import though, so not sure what happens if you upload a partial export (trimmed down to just the communities).

Note the import/export functionality referred to here is on Lemmy-UI’s (i.e. the default lemmy frontend’s) account settings page.

Frankly, the only sane option is an “Are you over the age of (whatever is necessary) and willing to view potentially disturbing adult content?” style confirmation.

Anything else is going to become problematic/abusive sooner or later.

I just download the offline installers from GOG and keep those on my NAS organized into folders per game until I want to install them. Not fancy, but it works fine for me.

You might consider using Google Takeout to export the emails to an mbox file, and then importing that into your new mail server.