I have a CPT "Locations" and would like the CPT to also be a taxonomy for ALL other posts/post types. The main point is to have the taxonomy always match the CPT "Locations" without having to manually create a taxonomy to match.
Lets call it what it is. CPT as a Taxonomy. Not Many to Many.
I've tried the plugin CPT-onomies https://wordpress.org/support/plugin/cpt-onomies/ Which seems like the only plugin I could find that does something like this. However, I don't think the developer is actively maintaining it, has some bugs, and is a tad overkill for what I need. I would like to try and achieve the same result with code.