The directions on everything in the virtual pinball community is always a slow drip of information from people who have MacGyvered something together and aren't always the best at explaining what they've done. Some information we found after some effort on forums and stuff could be expressed as this conversation:
Q: hey we're looking at getting an AtGames Legends virtual pinball cabinet. How do you nudge?
A: the nudge is a built in accelerometer! it works in all their built-in Android pinball tables!
Q: okay but we don't want to play pinball tables for Android, we want to play VPX
A: here's a video of setting up a Legends cabinet to interface with a Windows computer and run VPX. skip the first eight minutes where they introduce themselves and talk about what VPX is
Q: Neat! Okay wait but the person in the video literally never nudges
A: oh yeah uh, maybe you can configure some buttons to send keypresses that nudge?
Q: that defeats the point of having a physical cabinet though
A: (deep in a thread) buy this accelerometer off of Amazon, tape it to the bottom of the machine, and plug it in as a USB controller
can't complain, there is a solution even if it's weird, and the fact that information is actually on forums instead of gated in someone's Discord is a blessing