With Reddit's upcoming transition to a paid API model, users are most likely going to lose access to third party Reddit clients on mobile. Because of this, I feel it'll be important for Android users to be able to install Reddit Enhancement Suite, so that they're not stuck using the horrendous, closed-source, official Reddit app.
Apparently RES does work on Firefox Android, but you need to create a custom addon list in order to use it, which is only supported in non-mainline builds like Nightly and Fennec F-Droid. As well, I have had issues with addons not updating when I've had a custom addon list enabled on Fennec F-Droid.