Question about Xiaomi 5G CPE Pro

I don't know of any provider that assigns public IPs for the end devices for mobile (5G, LTM, etc.). This means that the devices cannot be reached from the Internet and forwarding to a server behind them is not possible.
This is usually possible with a cable-bound connection.

The router can do this, yes. However, whether it would work depends on the provider. I'm currently with Salt Surf, and there's no individual external IP, so the router can't be accessed from outside at all.