CV voices: a bit limited in usefulness IMHO. Audio rate modulation doesn’t contribute a lot and it’s not any particular volt-pitch scheme, but a more freeform sequencer like the SQ-1 can work.
CV delay: simple LFOs or smooth random are good, since the Hyper LFO is a bit odd.
Hold: any gates work well. It interacts with the hold knobs, “fast” switches and touchplates. Nice for injecting some synchronized rhythm.
Ext in: lots of stuff works well here with the Lyra’s distortion and delay. I haven’t had as much success with feedback patching the Lyra itself, but I admit I didn’t spend long on it (maybe hard limiting would help). Drums sound pretty great through it, and I’ve mixed drones from my modular with playing the Lyra itself.