VoiceAttack does not need to provide official support for any game, it is an application that allows us to create voice commands which perform actions which we have set for it to enact upon recognition of commands respectively.
I have not yet seen any public profiles for Arma Reforger posted here or on
VoiceAttack Discord.
VoiceAttack is great at pressing keyboard keys upon recognition of a voice command, and this could be used in any creative way you can imagine to say something and have a key or keypress macro enacted in Arma Reforger, such as controlling units. You'd start in the Arma Reforger controls screens to see what actions you can set to keys, and which ones would do well as a voice command instead of a keyboard key. Obviously, some actions we want to only control with our hands for maximum control over the time it takes to act, and voice commands are best suited for actions which are not extremely time sensitive such as commanding troops through keypresses or keypress macros.
There would not be any standard mappings beyond the default provided by Arma Reforger, and if you're interested in creating VoiceAttack profiles for public use, you might consider trying to follow these default key mappings as best as possible - or creating a way to read the user keyfile and parse each possible keypress and its callback to variables that can make your public profile work for any player regardless of their key bindings (with Event Log notes in VoiceAttack for those which are not yet bound and should be to use this public profile).
Best wishes and have fun!!