Hi there @serpa welcome back!
I’m not sure I can recommend a best approach here but adding all related logic to 1 action seems like it should do the trick!
You can certainly get all applications/clients using the Management API from within your action. If you go this route, you may also want to look into caching Management API tokens:
https://community.auth0.com/t/caching-management-api-access-tokens-in-login-action/95855
Hope this helps!