You can get a free account on portmap.io
There are some limitation to the free account. only one port no custom dns no cert
Paid accounts offer more capability. portmap.io
Basically you connect to their servers with OpenVPN and then they forward a port from a public IP to your device which can be behind NAT firewall.
Here is a ‘How To’ for OpenWrt setup forum.openwrt.org/t/howto-free-cheap-vpn-port-forwarding-for-starlink-type-systems-portmap-io/142244
There are some limitation to the free account. only one port no custom dns no cert
Paid accounts offer more capability. portmap.io
Basically you connect to their servers with OpenVPN and then they forward a port from a public IP to your device which can be behind NAT firewall.
Here is a ‘How To’ for OpenWrt setup forum.openwrt.org/t/howto-free-cheap-vpn-port-forwarding-for-starlink-type-systems-portmap-io/142244