Confirmed working solutions
Firefox for Android 68.11.0 (Fennec) works great with (at least) Violentmonkey. Should also work with other userscript engines.
Firefox 79+ (Fenix) versions broke add-on support
Iceraven Browser (a better fork of Firefox Fenix) works with (at least) Violentmonkey. Seems to be the new way to go since Firefox 79+ (Fenix) broke add-on support
But I’ve had some bugs that did not occur in Firefox 68.11.0, with which I will then stay at the moment
- Dolphin + Tampermonkey Dolphin add‐on: It was working in 2016 at least
Unlike Firefox on Android, Firefox for iOS does not support browser add-ons.
It seems that Apple doesn’t want any alternative browser engines on iOS, so there will probably never be any extensions or anything in support for user scripts, there.
I think Microsoft completely abandoned there mobile OS.
End of the wiki part, please do not edit my original post below.
Please post here if you know ways to use user scripts on mobile smart phones.
I am new to this kind of phones, I have always been using a simple but effective 40€ folding phone but now here I am in this smart phone new world (FWIW I have an orange coloured 100€ Microsoft RM-1075 Lumia 640 LTE Dual SIM X TURBO DASH).
I was first disappointed using a web browser without user scripts but then I read this news about upcoming OS version - via MonWindows.com - that would allow Tampermonkey on Windows 10 Mobile!
But still not sure if I understood well.