Interesting question, I had VST 2 working in Unity as an audio effect, and even vsti, but that was with a GitHub plugin that allowed this. From what I know, the pc version from Tranzient app uses a custom unreal built to support VST plugins. With interface and all. But having it in metasound would be the best. No interface is needed, just being able to control the basic params of a vst2 or even vst3 plugin, and having metering feedback would be even better. I would love to buy this as a marketplace asset.