With the vlemmy situation ongoing, i feel like it would be useful to put this here (i did not make either of these tools)
Lemmy Account Settings Instance Migrator (LASIM) copies all your subscribed communities and blocks and lets you upload them to another account, in just a few clicks
lemmy-migrate does the same thing but without a GUI and support for uploading your backup to multiple accounts at once
i used it to copy my subscriptions to accounts i made on a few other instances, even though i have no worry Lemmy.ca will shut down any time soon, as a just in case