

At work, we use PiSignage for a large overhead screen. It’s based on Debian and uses a fullscreen Firefox running in the labwc compositor. The developer advertises a management server (cloud or self-hosted) to manage multiple connected devices, but it’s completely optional (superfluous in my opinion) and the standalone web UI is perfectly usable.

That tells me you don’t understand what a “stable” release branch is. The Debian maintainers do a lot of work to ensure that the packages not only work, but work well together. They don’t introduce breaking changes during the lifecycle of a major branch. They add feature updates between point releases, and continuously release security updates.
In the real world, that stability is a great value, especially in the server space. You’d be insane to use Arch as a production server, and I’m saying that as an Arch user.
Something, something, sword of Damocles.