For audiobooks check out Audiobookshelf. On my NAS I run it in Container Manager (Docker) and get the image directly from the built-in repo. I check for image updates every few weeks, though only to keep compatibility with the apps, as I don’t notice new features. Very easy to set up, just make sure your folders are named correctly.
I’m coming up on 5 years as a Plex pass owner, so my users and I will not be impacted by this change. In five more years if they asked me nicely to pay another $89 to support the service I would. Send me some stickers and put a badge on my server. I get a lot of use out of the software/service, as do my family members.
I will say, I am quite annoyed at the wording and audience of this email. Jellyfin is just not an option for me until there is excellent feature parity with Plex. I know they are a lot of Jellyfin fans here, in my opinion, Plex is a significantly better experience for me.
I have the same setup with Picard --> mp3tag, it works very well for me. I prefer to overwrite the artist field with the album artist field for cleaner sync to my iPods with MediaMonkey (iPods handled multiple artists in the worst way imaginable).
Picard did take some light up front tweaking to get the directory naming to albumartist\yyyy - albumname\01 songtitle.flac but it was worth it