Hello Keycloak Developers,
I just found an easy way to use quarkus route based security authorization  feature with Keycloak.
It turns out that the security authorization feature is provided by the quarkus-security module, which is currently missing in keycloak.
In my custom Keycloak server build  I just need to include a dependency to quarkus-security (and it's dependency quarkus-mutiny) and then I can protect keycloak routes with simple quarkus configuration 
# Protect admin routes
# Protect welcome page
I think this could be easily added to the standard keycloak distribution - perhaps with some additional configuration mapping to make those policies configurable via keycloak.conf
Looking forward to your feedback :)