I think it would be better to move budgie applets and budgie themes from budgie welcome and integrate it directly into budgie desktop settings as a full fledged applet and theme center. Linux mint Cinnamon shows how this can be done
I agree with you here - but this is not really in the current Ubuntu Budgie team’s expertise here. It will need very good Vala skills to make this happen.
We are dabbling in Vala at the moment - but not at the level to make such a substantial change as this request will take.