If you’re not already aware of it, be sure to look through this Ni-Kunni article and the Mishi IV article for general ideas. Ni-Kunni have some of the most fleshed out stuff so there’s a lot to work with.
Edit: And note, of course, that attempts to revive a Ni-Kunni religion are not going to be thought of fondly in Amarr, as they purged most elements of it when the Ni-Kunni were integrated. Most attempts to rebuild traditional Ni-Kunni culture take place in the Gallente Federation. This doesn’t affect things like structures in space due to capsuleers being independent, but just noting for how baseliner Amarr/Ni-Kunni groups are likely to look on it.