Well, I tried setting up @wallabag via docker-compose using a Tailscale MagicDNS address as the TLD and it didn't go particularly well, but no harm no foul there, I knew it was a long shot.
I'll try again using the old school by-hand install instructions that are the default and use Cloudflare to actually tunnel out to a real honest to god internet accessible TLD and things should go better.