Last year I discovered big crayons for children that you erase with water. They are awesome.
I do not know brands in the US but in France this would be something like https://amzn.eu/d/7L7p2Cd
I use them on various surfaces, they work best on whiteboards but are all great on windows (and you look cool then).
The only small drawback is that you cannot erase a small mistake with your finger (out au least it is not that great).
I love them and got some for all my teams.