I am sure its not THAT strict but what are your thoughts on a slightly bigger hex map, with at least 20 keyed hexes? I recently did a jam where the hex map was pretty small so would like to make something a tiny bit bigger maybe.

Go for it! I picked 20 hexes because it seemed like a reasonable but still challenging goal when combined with the dungeons. If you want to try for more, go ahead and give it a shot.