I think a good approach rather than working on many small apps is to find a niche with a large enough audience and create a utility app valuable enough that people would pay you a subscription. Validate it by first finding an audience, ask them if they would be interested in it. If they are, create a mvp that doesn’t take long to make. Charge a price for a small feature set within the app. If they do like it/ use it. Build features on top and eventually create a subscription. The reason the App Store is so crowded and looks like it’s not profitable is because everyone is copying each other rather than finding a specific niche and provide that niche value. If you find a unique niche, then you won’t have any trouble getting a side income, and who knows eventually make it a sole income and get your time back.