Using an engraving tool like the #501 might be good. Just pretend it’s a 0.01" ball nose.
Otherwise, I’ve used small tools before from Kodiak cutting tools. And at that size, Datron single flute’s are actually pretty cost competitive too. Single Flute End Mills - DATRON CNC Milling Tools
But on a Shapeoko you’ll want to double check your runout to make sure you’re not over-stressing the tools.