Welcome @TopQuark!
Check out GitHub - pfaffman/discourse-custom-homepage-for-groups: Discourse theme component to change home page based on user's primary group · GitHub, which I suppose I should make a post in Customization > Theme for. A client combines it with GitHub - literatecomputing/discourse-ucf-group-assignment: Update group membership based on user custom field · GitHub to allow users to choose a value in a user custom field which automatically assigns them to the group which the theme component then uses to select their home page.