Yeah of course if it's c++ dsp, you can just use a global cable to send the graph to the UI
Keep a second, mono class of the compressor dsp without envelopes, and when a paramter changes, compute the response (staggered updates) using that instance and send it as a json to the UI side of Hise.
But you can even do this in Hise if you want. I doubt the compressor algorithm is complex. Just write it as Hise script and process your line through it.
Without envelopes, a compressor is a waveshaper. It'll just be a simple algo