It does run on the new MacBook Air/Pro with the M1 processor, but not all features are working.
You simply download the SD app from the app store (there is now a tab for iPhone/iPad apps). It launches in a window and works as on your iPad. The window is resizable to full screen if needed.
I have not fully tested the app but, as far as I could see, its main features are working and are very fast.
Things like popping up documents (e.g., plates), getting your GPS position or printing pilot logs are not working. This is probably due to SD leveraging other iOS apps that are not available on MacOS. Not being capable of accessing the plates (SD, Pooleys or AFE) and printing pilot logs is quite limiting for flight planning. Note that geo-referenced plates can be overlaid on the moving map and display perfectly.
At the moment, it cannot compare to SD on Windows (or on iPad) and it uses one of the two mobile licences that you have available to you when purchasing SD. So probably not worth it.