You're not going up against "how hard is it to roll your own", you're going up against "how inconvenient is it compared to Zoom". You can spend millions to make something that works but unless it's as good as Zoom is (and that's going to cost you a few million to develop from scratch, even with off-the-shelf FOSS components, and FAR more if you're hiring experts to write it scratch) your CEO should, and I stress *absolutely should* (because their responsibility is to shareholders, not to employees) go "how is this better than zoom, and why are we not using that instead so we can put that money in our own wallet?".