Isolating New Users from subwikis

Hello,
recently I’ve been trying to create an XWiki enviroment where using Keycloak groups I would put the users only into certain subwikis, not allowing them to search and explore other subwikis.
Using Keycloak creates global users, and so any extension or search and even a mention looks up for every user in the wiki and that should not be the case.
The perfect scenario is that only admin could explore any subwiki and groups could be put into subwikis chosen by the administrator.
Revoking rights to global wiki and granting them for certain groups in certain subwikis result in users not able to scope for local users using extensions etc.

Is there any workaround without the necessity of modifying the code?