Vaultwarden keeps an encrypted file local to the device you access it from, like your phone, and if the instance goes down you’re still able to access them but not add new ones. This let’s you export the file into a replacement instance.

I’ve used both podfetch and the project it’s based on podgrab. They do well enough but in the end what worked best for me and sounds like what’s best for op is audiobookshelf.

Just a few days ago i finally added my podcasts to my Aufiobookshelf instance and i’m kicking myself for waiting so long to do it.