MK3 and MK4 power armors (bigger grid, larger inventory), also adds various equipment (Night vision MK2, Energy shield MK3, Fusion battery, Singularity...)
I'm not sure either tbh, maybe submit a pull request on Github? It would be pretty neat if we could get a few new items or features that aren't just 'MK+ item'. If things go well I'm open to inviting you to be an official collaborator. Feel free to open a discussion on Git or the forums if you want to discuss ideas, PMs are fine too.