not at the moment, an assignment kinda works as an “opt-in” for users saying “yes, I want to receive popups from this plugin if needed”
allowing any plugin to open a device popup at any moment can quickly get out of hand..
mod-host uses LV2-Extensions/kx-control-input-port-change-request.lv2/control-input-port-change-request.h at master · KXStudio/LV2-Extensions · GitHub as a way to support this.
API is pretty simple, should be straight forward.
But if you have issues let me know.