Help structuring config

How are other people handling things that are common to all of their hosts? I have a common directory with home and os in it, and both get imported by all hosts. I have some of them disabled by default too. It feels a little bit messy to me though, and there are weird things like me having to do home-manager.config.<user>.custom_option within my host config, and that feels wrong. Am I overthinking this?

Also, how do I handle situations where configuration will be weirdly split between home-manager and nixos options? For example, I have to have a gaming module for both hm and nixos because there are relevant options for both.

Here’s my config: PopeRigby/nixos -