I think a slightly bigger monitor would be nice, but it’s definitely not a must have. I don’t have trouble with using the UI with my fingertips on the 10" at it’s native resolution. All of the primary 1F controls are easy to press, and it’s easy to read. That said, you do need to scroll down to see the gcode part of the UI, and some of the native controls (like when you’re selecting files from a USB stick or something) are a tad smaller than I’d prefer.
I used a monitor mount I found in a trash pile, so I don’t know the brand. Lots of similar choices on Amazon, though. Lemme see if I can post a pic. Also, note that I’m only a few months in to the 1F and CNC woodworking. Those with more experience might have more informed opinions…