Just in case anyone is interested, I built this plugin that uses your Primary Group to set your homepage to be the Category that’s set up for that Primary Group, resulting in a “User-specific” (aka Group specific) homepage.
https://github.com/merefield/discourse-category-home
It’s not battle tested and I’m not sure if I will support it unless someone wants to fund the work, but feel free to install it and try it out :). If you like it, at least 
it 