You can only install add-ons from the AMO store.

Thanks for the reply, interestingly the app check4change is available as addon on my PC Firefox but not showing up in add-ons in my android, so developer created the Xpi file.

Hi

There is currently a limited number of add-ons available for Firefox for Android but we hope to make more available very soon.

Thank you for the info

Can you install it from this URL?

https://addons.mozilla.org/firefox/addon/check4change/

Negative I tried that already, I have Firefox installed and when I hit your link it tells me to download Firefox and takes me to Google play Firefox app and since I have it already installed it gives me the option to uninstall or open Firefox, that's why I downloaded the Xpi thinking maybe I can execute the file and will open in Firefox, I 3ven used a file manager and when I double click on the Xpi file it doesn't give me an option to open with Firefox in the file manager

Is this version 120?

Firefox is 119, Beta is 120

Ah, you have to wait few days.