From experience, Shopify's app store is great for developers who want to build something and don't want to involve themselves into thinking about distribution.

From experience, Shopify's app store is great for developers who want to build something and don't want to involve themselves into thinking about distribution. It was one of my first forays into building a SAAS, and I was able to scale to 5-figure ARR. Churn is incredibly high, unfortunately. And merchant reviews are ruthless. There's some consensus amongst Shopify devs (at least in a particular Facebook group) that Shopify isn't doing enough in weeding out unreasonable reviews and fake reviews. So it's quite possible you launch your app and get killed in your first week. I've experienced it (as well as others) where merchants take you (the dev) hostage by threatening to write a poor review (which will affect your ranking) if you don't create a feature just for them. I no longer need to develop for their app store anymore, but it's still a good start if you're just breaking into side projects and want to monetize them.