Several individualized (login) Front-End and differrent (sub)domains on a single managed nextcloud (ionos) - possible?

I have several managed nextclouds running on IONOS for several small NPOs.
For every NPO I have an individual paid contract with 500G or 1T, why I want to use one single managed nextcloud but keep the front-end individualized.
Id organize the rights via group(folders) (no problem, even welcome, that users can see other users)

Idea
Every (sub)domain of each NPO should show the user an individualized login-screen
egs. npo-cool.my-managed.cloud, npo-hot.my-managed.cloud and www.npo-top.org
should each

  • point to an individualised login-screen (corporate design)
  • be usable as serveradress for syncing with the NC-client etc.
  • Bonus if possible: have an individualised design in nextcloud (egs. colours)

Is there an NC-App enabling this feature and/or with DNS Ressource Records?

Thank you already!