I have noticed that it is possible to use a custom taxonomy for a user. I need to save the location to a post, but using the custom fields I can then attach that taxonomy to a user. I have previously understood that this is not a normal function of WP. And so I just want to double check that if I create a bunch of taxonomies to only use for user (eg - nationality, gender), then I do not cause later issues!
WordPress does not allow registering the taxonomy for the user like the post so the field taxonomy does not work with users. But you can try to use the field taxonomy_advanced, it works like a user meta. Please get more details here https://docs.metabox.io/fields/taxonomy-advanced/