Firefox Preview mobile browser will soon support extensions.

Mozilla developers have published implementation plan for add-ons support in mobile browser Firefox Preview (Fenix), which is being developed to replace the Firefox edition for the Android platform. The new browser is based on the GeckoView engine and a set of Mozilla Android Components libraries, and does not initially provide the WebExtensions API for add-on development. In the first quarter of 2020, this shortcoming is expected to be addressed, and GeckoView/Firefox Preview will feature tools for connecting add-ons, providing sufficient functionality to support add-ons from the recommended list.

Source: opennet.ru