There is a market but not for the hobbyist. You have better luck on iOS than macOS for games. However, tools, you can make a killing selling simple tools with sexy UX on Mac.
I've been thinking about doing something like this recently but I'm not a heavy mac user these days. Any tips on what people are looking for in small tools?
Ask yourself, what tools can I build that are not only useful to me, but maybe useful to others, and start there.