Correct. You can run Syncthing and Nextcloud for your own cloud server.

You can run Vaultwarden which lets you host your own Bitwarden instance.

You can host Gitea to have "your own GitHub" so to speak.

You can run LNBits and BTCPayServer to sell stuff for Bitcoin and a lot more.

You can run a lightning node of course.

You can run your own Nostr relay.

You can run a local instance of Mempool.

You can run encrypted messengers including ones integrated with lightning like Sphinx Chat.

You can sell access to files.

You can use Joinmarket with a friendly UX.

You can run your own media server.

Your own search engine.

Your own blog.

Robosats locally.

And more.