The one company I worked for over 300 people that held a weekly meeting made it entirely optional- it was an end of the week, end of day Friday meeting where someone would give a demo of either something cool they built or a success story for a client. I don't believe more than half the company showed up on a regular basis, but it was a really nice social hour for people who wanted to partake.
This predated COVID by many years, and remote work was only just becoming a thing, so we had custom built video streaming software once we opened additional offices so that the whole company would see the demos, if not so much the in-person chatter and snacks before and after.
I really like this, especially when overlapping/doubling as a social happy hour. A former company did something similar, I always enjoyed seeing what other parts of the company were up to.
This predated COVID by many years, and remote work was only just becoming a thing, so we had custom built video streaming software once we opened additional offices so that the whole company would see the demos, if not so much the in-person chatter and snacks before and after.