It's possible since XWiki 15.3 in standard or using https://extensions.xwiki.org/xwiki/bin/view/Extension/AuthServiceBackport/ for older versions to indicate OIDC as the authenticator at wiki level (so for example in a custom flavor). See https://www.xwiki.org/xwiki/bin/view/Documentation/AdminGuide/Authentication/#HChoosetheauthenticator for more details.