Great tool. Using it all the time!
A few usability suggestions, maybe these have already been suggested.
When pasting copies of ink it would be very nice to select the location where these get pasted. Right now have I to find blank space on the page to avoid placing on top of existing strokes.
I'm using desktop with a tablet. It would be super nice to be able to pan on the page using keyboard maybe with the arrow keys.
I like the ruler but it takes some effort to dial in the angle. One idea to speed that up is to double tap on it to allow typing in the angle.
Most importantly there maybe lots of feature requests but what I really like most about it is that it's minimal and simple to use. Please try to keep it that way.