Tried 1.16.5 stable on my M1 air yesterday. Here are a few observations:
Requires launching via `mono vintagestory.exe` otherwise mouse is unresponsive in game (works in menus, but not in game)
Block outline indeed makes the HUD disappear - the option `selectedBlockOutline` works as a workaround
Knapping is almost impossible because the HUD disappears there as well (probably same cause)
Game at 2560x1440 regardless of video settings runs very sluggish, e.g. the mouse has input lag of I'd say about 100ms and visibly trails movement with the hand
My suggestion to you: drop the macOS support, I doubt it's worth the effort to get it halfway as stable as the Windows version. You'd probably save a lot of time that you can spend on improving the game.