I have set up a minecraft bedrock edition server on my android phone by setting up nukkit in an ubuntu for ARM being emulated in termux terminal emulator for android and it runs pretty well and I can connect to it from my own device. But now I want to port forward it so that it is accessible from anywhere in the world, but guides online say that you need your router ip...blah,blah,blah but I dont have a router, I am using the 4g network provided by jio. How can I get my server running online?
Use the ifconfig command baked into basically every android version. You can access it by installing a terminal emulator. However, you might not be able to access the Server running on your Device due to your provider blocking incoming connections to all mobile devices for "security reasons", or at least that is what my provider told me when I was trying to host a http web server on my android device.
On 4G network you don't get a public IP (mostly) from your MNO. So your phone won't be accessible from internet. Related: How to connect to Android through SSH over 3G/4G public IP?.
However if your device is accessible from internet, you don't need to do port forwarding. It's required only when you are behind NAT (router), but you are directly connected to internet. In case you create hotspot on Android and run server on some connected host, then you can forward port this way: How to port-forward internet using android Hotspot?