This repository has a ton of awesome-sounding Budgie Panel widgets that we don't have, and a nice, centralized build script that will build all the modules in one sweep.
We have a package.yml for this already. It's done by @algent and available the budgie-extras source repo on our development tracker.
Is this package missing for any reason? I note we have the appstream-glib/appstream-glib-devel packages.
Our appstream-glib is really only used for specific file generation for the Software Center. It shouldn't be necessary otherwise, appstream files should already be generated by the developers, and only the binary is required for updating the appdata via usysconf (which it already does when there is new metainfo).
Further, would a Solus fork of this pre-compiled and available in Software Center make sense to anyone else other than me?
No. I don't want everything in budgie-extras shipping in the Solus repository for various reasons, whether it's that I don't see a value-add in them, they're not up to my standards, they require old libraries and utilities we aren't going to be including, or they are redundant compared to Budgie core functionality that should be improved over having separate apps. I don't want a fork of their applets, I'd rather improve what we have. What we have from this is what I've personally accepted to be included.