> I miss the ability to set arbitrary shortcuts and bind them to arbitrary menu items.

In each application? Interesting that the OS provides that.

  > macOS is frustrating to use without a mouse.

My experience confirms this as well. I was really expecting an ergonomic, well-polished experience but I found that the Mac is polished like shark skin. It's nice and smooth if you do things - or can force yourself to do things - like the engineer in California does things. But if you like to keep your hands on the keyboard, or organize your applications (not just windows but applications), or anything else then you are going against the grain and that smoothness turns into obstacles and pain points.