I have great news: The migration went through all of it without errors. I’m the proud owner of an up to date Yunohost server thanks to you!
I just had to create new users, the former ones were obliterated from reality (but I got to keep their /home/).
I also had to recreate all my domains, and I have few apps that prevent me from login because the users are not existing anymore. So I might have to reinstall stuff from scratch and reconfigure.
The major issue I’m encountering is the 504 error when trying to log in to the weblogin. It’s preventing me to access some of the admin only app, and it’s a problem. But at least I have my yunohost running with the main apps.
Edit: My 504 error is exactly the same case depicted here: Erreur 504 via yunohost/sso portalapi (debian Bookworm) - #38 by valen
With all the commands returning the same. Such a shame there is no solution provided. Setting NGINX to “modern” didn’t solve it.