Ref general discussion thread:

Suggestion is pretty simple:
-Add grende trajectory indicator
-With greande in hand or in the throwing stance "FIre Button Key (Mouse1)" pressed, press the "Cycle firemode key (V)" to cycle between regular throw and underand throw modes
-With "FIre Button Key (Mouse1)" pressed trajectory indicator is displayed, scrolling the mousewheel will increase or decrase the throw strength and change trajectory indicator
-With "FIre Button Key (Mouse1)" pressed, pressing "Perform Action Key (F)" will cook the grenade

Here is an excellent video from Dslyexci on the ACE grenades: 
https://www.youtube.com/watch?v=Gu4P2rhyXiI

Hope something like this makes it to Reforger or Arma4

-Thank you for reading!