How do I archive a podcast I've already downloaded in Playapod (iOS) that has since gone offline?

Hello c/datahoarder! I need your help. Not sure whether this has been asked before—I've tried searching the web, but the only advice I can find is how to download episodes for podcasts whose feeds are still active.

The problem I'm trying to solve is that one of my favorite podcasts, Endless Boundaries Jam Radio, went offline during the pandemic. All the usual feed aggregators still show up in internet searches, but as they are not file hosts, just feed aggregators, all the episodes are now dead links (e.g. Podbay, Tunein, etc).

Thing is, I had already downloaded several episodes using the Playapod app on my iPhone. It's usable for now, but I'm very concerned about when I need to upgrade to a new phone.

Is there a trick for access the individual files on my iPhone that were downloaded through a third party app such as Playapod? TIA

EDIT: I figured out how to do what I wanted. Once I had installed ifuse and related dependencies (e.g. libimobiledevice) on my Linux PC, I could connect my iPhone to my PC via USB and browse the files on my iPhone in my distro's default file browser. Many folders are named as GUIDs, making it harder to tell what's what by just looking at their names, but I narrowed down the right folder by opening up the Disk Usage Analyzer app in Linux. In my case, the Playapod app is one of very few apps with more than a gigabyte of data. I still have to go through and figure out which episode each mp3 file is, but that's still better than having nothing at all.

Thanks to everyone who responded. I hope this info helps anyone else in a similar predicament!