Glyphs is like the only game in town for font editing. I’m an Omnigraffle enjoyer too.

There are lots of amazing Mac only apps, but I'm not sure simply running them on Linux would be worth it. Without the cohesiveness of the UI as a whole you'd be losing a lot.

For me it’s mostly media apps - Fireworks CS 6, Reason 10, maybe some version of Garage Band. There’s alternatives but these apps hit a sweet spot that I could camp out on for decades if the tech treadmill didn’t like to make software an exercise in seeing shifting shapes in the clouds.