Thanks. I think I get the XML data layout. I can manually add a published RSS feed within AntennaPod. Is that what most listeners do? Or do they use the indexing services and generally stay within that garden?

If you use a publishing service like podhome or wavlake they will automatically push your tracks to the podcast index. Once there, all the other podcast2.0/rss compatible apps will pull your music. Instant automatic wide distribution. You can also choose to manually push that same feed to any other service you like such as antennapod. It really depends on what your goal is in terms of how far and where you want to spread your content.

Oh, I didn't know they didn't realise they were walled off like that. Their content policy wasn't very encouraging either. It did seem that wavlake had made a recent change around their custodial wallet. Seems it's only available when you are "region verified" to a region that isn't blocked. However you can choose to forward to a different wallet without verifying at all. At least that's how I read it. But yes, the wall alone is enough to make me move on. Baby steps.