I quite like this and I feel like you could go one better and have optional people be "on call" during the meeting i.e. they should be available to ring in if needed.
We tried that initially and there was just a bit too much friction involved in them finding the zoom link and then joining and then getting their mic connected and everything. It was easier to just have them join the meeting in the beginning and be muted so it was ~5s for them to hop into a convo.