I tried switching a game from in person to online a few months back playing mainly via discord (due to poor internet connections, otherwise we would have used video) with Roll20 for visuals. I was running Star Wars Edge of the Empire which does not use grid-based combat, so battlemaps were less important. Long story short, the game fell apart when one of the players decided the game did not work with his schedule.
I talked with him recently about playing again and he said that he felt that a lot was lost when playing online vs playing in person. I asked a separate question about that a few days ago and that sparked the question:
What can I do in a session zero to let players know what to expect when roleplaying online?
Of particular concern are how to prepare
people who are new to roleplaying
experienced roleplayers who have never played online