How can I use userscripts on Firefox for Android? As of October 2020 I can't seem to find a working add-on/extension for Firefox on Android. Tampermonkey's page says the add-on is not compatible with Android, but I think it used to work fine a while back. Is there any way to install userscripts on a current version of Firefox for Android (including beta or developer editions)?
If current versions don't support such extensions, and the only way is to install an older package (not recommended due to potentially unpatched vulnerabilities, I know), which is the latest package version I can use Tampermonkey (or a similar) extension with?
End of August Mozilla has pushed a new major version of Firefox for Android that bases on a new web engine.
For an unknown reason for this new version they only allow a very small set of hand selected addons. May be the engine changes were so big that most of the addons now have problems?
It seems like the developers at Mozilla are trying to bring back the full addon support in the next version which is scheduled for October 22th. According to the Mozilla blog the current Firefox Nightly version should already include the mentioned full addon support. May you give this version a try - hopefully it will be able to run Tampermonkey addon again.
As you have already pointed out installing the old Firefox Android version is a bad idea because of a extreme severe vulnerability which allows to remote control Firefox by any device in the same subnet. Therefore the only chance I see is to try out the nightly version or wait until October 22th for the final version.