No, it is clear what you want to do. It just cannot be done. That is not the purpose of myopenhab.org and the cloud connector binding. Only the OH REST API gets exposed to myopenhab.org. It is not a full reverse proxy and probably never will be.
Well, frontail is not part of openHAB, nor is Grafana nor any of the dozens of external web based applications people have on their LAN and may want to access on their sitemaps. But that isn’t likely to ever happen because doing so is very challenging to do securely and would require orders of magnitude more server resources than our already somewhat stressed myopenhab.org servers are under.
If you want to access these outside your LAN, you need to set up your own reverse proxy. You should be able to use the OH reverse proxy docs to add additional services to the reverse proxy.
Alternatively, you can set up an ssh tunnel or a personal VPN to access these services when not at home. Personally I recommened one of these approaches over the reverse proxy approach. If you don’t have the knowledge and skills to know to set up a reverse proxy already, you probably do not have the skills and knowledge to secure the reverse proxy and monitor it for compromise.