Absolutely wonderful. Works straight out of the box, thank you so much @Canapin for bringing the topic here and @Don for the precise answer. I used the APK functionality to use my forum as an app, so now I essentially made my own messaging server. This is absolutely insane.
Also, thank you twice @Don , because this plugin also does other things which I really needed (the last time I saw the development of that plugin was 2 years ago… men, time flies…)
Thak you both again!!! 
(and sorry for the delay in my answer 
)