Journalctl has a bunch of filter options that you should take advantage of when troubleshooting. For example, journalctl -b -1 will show you only the messages from the last boot (not the current). I used this article for a quick couple of need to know commands. Enjoy! :D
Good news, they support OIDC! Haven’t tested it myself so your mileage may vary.
https://headscale.net/oidc/#basic-configuration