I added these comments to the Moonbeam video on YT. My ears perked up while I'm looking at a "True Shillelagh" build (Shillelagh+True Strike).
I'm unsure this works to sweep out an area. RAW in PHB under "Breaking Up Your Movement" only discuss splitting movement before/after Actions, Bonus Actions, and Reactions. However this is character movement. I haven't seen in the books about breaking up movement of non-creatures like Moonbeam. So as you sweep up the example room, each 5' movement takes a turn? Intelligent monsters might notice a pattern, and use their turn to move to a space that has already been swept. It's still a nice tactic. Completely agree about Druid being solid.