In the Firefox Preview mobile browser, however, so far only in nightly builds, the long-awaited ability to connect add-ons based on the WebExtension API has appeared.
In the browser, a menu item "Add-ons Manager" has been added, where you can see the add-ons available for installation.
The Firefox Preview mobile browser is being developed to replace the current edition of Firefox for Android. The browser is based on the GeckoView engine and Mozilla Android Components libraries.
Source: linux.org.ru