My apologies if this is not the right list to ask this, but are there any plans to build Plasma 6 packages for kde-unstable now that it's being shipped in unstable KDE Neon releases and the nightly/testing repos of a few other distros?
I guess that's mainly Antonio Rojas' decision. Likely he would create such packages as soon as there is an official alpha/beta release. I would like to see such packaging myself. However, at this point it would only make sense to me if such packages would be co-installable with the Qt/KF 5 versions. I've already seen AUR packages but they don't appear to be co- installable.
On the same topic, is the kde-unstable repo still an official repo? It's listed in the Wiki, still shows up as a repository on archlinux.org/packages, and still syncs through Pacman, but it has no packages (I'm not sure for how long) and I noticed that it's also missing from the Gitlab instance containing packages for the other repositories.
I consider it official but of course you should not complain if it is unstable (and rather be prepared to file upstream bugs). This repo usually contains alpha/beta releases of Qt and KDE packages but might be empty if there's currently no alpha/beta. To get a Plasma 6 environment under Arch for porting Syncthing Tray's "plasmoid" to Plasma 6 I so far used a very hacky but also very simple approach: https://paste.opensuse.org/pastes/d4bcf35ee634 - This is of course not what you have asked for but maybe still helpful. To use the manually built/installed binaries you'll have to execute the "prefix"-script CMake will tell you about (otherwise Plasma will not be able to find all its files under the custom install prefix).