Access auth backend in template

[UXabre]

My Goal
I’m currently trying to work through a use-case in which I’m using Keycloak (and thus JWTs) to authenticate against different realms (multi-tenant). I configured my jwt backend to copy some claims to the metadata section, as I’d like to simply write a single policy which applies to all customers by using template variables which substitute a part of the resource path with metadata claim.

The Problem
However, I noticed I can only do this if I know the backend-id (since jwt metadata isn’t available in the identity metadata); however, since this is multi-tenant, and I’d like to prevent my provisioner to be able to create a policy for each tenant (as this could lead to my provisioner writing a policy which allows admin rights!

The solution?
But I also saw that , using /auth/token/lookup-self we see the metadata for my jwt, which looks as if there’s a way that I should be able to do this in my template as a substitution variable, without me actually having to know the auth backend. Not sure if anything like {{token.meta.claim}} exists or if anybody knows a workaround for this?

[UXabre]

This one also looks very similar to what I suggest and even provides an actual suggestion:
#10460

I'm currently investigating the code and check where and if I can create this