The way I’d attempt to do this is probably to keep track of the value in two time periods, one in real time and one slightly delayed. So if you gradually move the stick, those values will be closer together, but if you push it all the way and let it go, the values will be a big difference. So with a tolerance and speed that works for you, you can set it up to check those values against each other and then branch out behavior.
That’s what I’d try and see how it works. But to be honest I don’t know if there’s any better way to do it. I’m assuming you’re talking about using Blueprints. So with that, unless there’s a “get stick speed” node, you kinda have to slap something together.