Add extra functionality to any URL in Android using Termux's URL handler
If you install Termux, you can find it in the Share menu.
Sharing a webpage to it runs the shellscript bin/termux-url-opener, with the URL as argument 1.
You can do whatever you want with this URL in this script.
If you want to pass a different URL back to the browser, you can call termux-open or termux-open-url with the new URL as an argument.
The example opens the current YouTube video with LoopTube.
sleep 3 is needed at the end, since otherwise Termux would close before the new URL could be opened.