When I connect the Surface Keyboard to macOS, it seems to go fine, I enter the pairing code and everything works, keyboard works.
However I want to switch the modifier keys (Option and Command) to work like the Mac keyboards, and I can't do it, because macOS seems to not realize this is a keyboard. The icon shown in the Bluetooth preferences is the generic Bluetooth icon, and this keyboard is not listed at all in the Keyboard preferences.
Note the Surface Keyboard claims full compatibility with macOS, (see link above), so I'm not sure what I need to do to get it fully recognized.
Best Answer
I found that I could remap the keys using Karabiner Elements. Credit to this blog post.