Not trying to convince you in particular of anything, but for anyone who may be interested in switching to a different podcast app, I'd recommend trying Antennapod.
I've considered this as well, as I already back my data up regularly. However, I read online that external disks aren't good for long-term access. Have you run into any issues with that?
Thank you for the suggestion, I'll have to open up the machine to see if the motherboard has a SATA port. Adding a second SSD doesn't sound too hard assuming it is possible.
Would scrobbling to e.g. ListenBrainz (or last fm) be an option for you for discovery?