I usually add refineries to my rural-focused worlds, especially when they have a large number of deposits. If most of your pops are working in districts, you can end up with pretty sizeable populations with lots of spare building slots. You may need a city district or two (unless you have agrarian idyll) to house the extra pops.
Habitats are also pretty good at this. A habitat focused on alloys or consumer goods won't be able to house enough pops to work full complement of these buildings if fully upgraded, but it can support the 75 pops to unlock all building slots, so you can build about a 60/40 split between your factories and the refineries that support them.