Looking for ideas on how to manage rooms

A non-profit club that uses nextcloud is moving into a different location. They are looking to somehow manage the rooms in the new house. They will soon have access to two more houses to offer their services to the public.

Sometimes rooms are used for their own projects and courses, other times they are being used and rented out to others for their projects and courses.

Other than the calendar app (and adding rooms to the resources), how can they get a collaborative overwiew about which room is in use when by whom?

Is there any app than can be used for that? Is there maybe a third party app that has nextcloud integration, or is integrated via an app into nextcloud?

They basically want to sort by rooms, and not by dates. That is the primary objective for what I am looking for.

Is there an already existing app, that would make this possible without getting too cluttered after just a few months of using it?

Thanks in advance for your suggestions. Even if they are “out there” they might give me some inspiration on where to look next. I mean, we’ve got cookbooks - so there must be something out there already that I have overlooked that can serve that purpose.