Voyager for lemmy is now on F-droid! You don’t need to setup a third party repo as its in the main repo
Edit: I’ll just stick to Jeroba for now as the Voyager UI is painful for me personally
Unless the app allows you to export/import your settings, unfortunately the answer is no.
This is because F-Droid builds its own installers and signs them with their own key. Android (sensibly) does not allow upgrading a package if the signing key is not the same.
Actually, Voyager has reproducible builds enabled. This means F-droid distributes the app with the same key that is used for everywhere else Voyager is distributed (Github releases, Play store).
So if you want to migrate from Play Store to F-droid, turn off automatic updates for Voyager in Play Store and update the app with F-droid :)