Well, for me, I bought a $5000 top mac laptop 2 years ago because it's the best choice for my work, and I expect it to last for another 7-10 years and it doesn't make much sense to buy another computer for a few games.
I think a Mac version is underway. On Epic store, Browse the store, choose OSX at the filter, you can see M&B II with a "coming soon". So I am quite optimistic about it.
No, proton doesn't work on mac. And wine doesn't work very well either. I tried to use MS Excel with wine once, and....Nah. Warband has a mac version, so I think they can compile a mac version right? Don't know what engine they used for the game.