As far as the ui is concerned, basic authentication is certainly enough at the beginning (maybe everything also with nginx). A little more sec+ with fail2ban or IP restriction. A nice interface around it can come later, or embed it in an already existing one. Gradually expand more and more, depending on demand. This is the most cost-efficient variant.

See also -->

https://www.server-world.info/en/note?os=Debian_12&p=nginx&f=11

and

https://www.server-world.info/en/note?os=Debian_12&p=nginx&f=5