In reply to Rob Parsons:
It can work, it just needs a bit more management of how things operate, ie someone has the floor for a while, then comments from the room, then questions from online use a react or hand up function and go round.
To answer the OP - Zoom works pretty well for this, as for ancillary tech it depends a bit on how many people are there. I've done something like this for an event with two cameras (connected via USB, can change between them using the drop-down menu in Zoom) and a PA system with a couple of mics to hand around. If you're adding any tech on the audio side it's very important to not send the Zoom sound back to itself, it can be helpful to draw a picture of how things will all connect and interface