Is there any way to run an extension for debug on Android FireFox?

[juraj.masiar]

Also note that you need to use Firefox ESR 68 in order to debug current Firefox for Android.
More info:

Is Android debugging still working?

Hi! Yes, remote debugging should still work fine If you are trying to debug Firefox for Android on your emulator, be aware that it is based on Firefox ESR (v68), so you need to connect to it from Firefox Desktop ESR68. You can download Firefox ESR at https://www.mozilla.org/en-US/firefox/all/#product-desktop-esr Our backward compatibility policy only supports a gap of 2 versions. This means that Firefox for Android (aka Fennec) can only be debugged from: Firefox 68, Firefox 6…