As for migration, you might be able to create a degraded pool initially, copy over the data, and add the parity disk last.
I actually asked in the TrueNAS forum about this idea. According to some knowledgeable users this might work. For anyone interested, details here. The next major release (planned for end of October), should make this easier.
Podcasts partner up with ad providers. They inject ads into the episodes depending on several factors, including your location. The podcast has some say and can for example exclude some topics like politics. That catches most, but an ad can also be misrepresented and slip through.
I use Antennapod as well and they have nothing to do with it. They just download episodes from RSS feeds provided from other services.
You could use a VPN server in a smaller country. If the ad market is very small, there simply might be no ads to serve you.
I can also recommend using a swiss VPN server. The funny swiss dialect makes it hilarious.