Is it possible to stop a parameter with velocity if it's at a certain value? (e.g. 0.25)

I’d like to sustain a parameter with velocity at a certain value, but allow it to continue if the parameter is then set from the game to a higher value

No it’s not, but what you describe could probably be achieved by seek speed instead of velocity.

ah wait I can just do that with a sustain point and key off on the timeline

nevermind xd