I just saw that ipfire 3.x plans to include OpenLDAP, which is pretty cool.
But maybe instead of trying to reinvent the wheel by making a custom UI for it, it could be considered to add Yaal / Canaille · GitLab ?
It is a really nice web-frontend front-end for OpenLDAP that is written in Python, so supporting it should be not too hard. And it gives additional support for OIDC/Oauth2 out of the box as well.