Questions about how tunnels work for VPS

I have a docker server installed on linux and wanted to host it to the world.

Problems- I can’t port forward, and i don’t have a static public IP.

I know tunnels get raid of the port forwarding problem. but does it also work around the DDNS or would i need to install cloudflares API.

And how can i make this work with nignx?

When you create, tunnels, you create a CNAME DNS record that points to the tunnel which will handle the changes of IP.

You can forward your traffic from the tunnel to nginx if that is what you are asking.