My business is in my bio, don't want to link it here. Pays about the same as my previous job at Microsoft did, but with a lot less involvement — I haven't touched the main code in about a year now. I probably spend about two or three hours a week on customer support, that's it, really. No marketing spend, all word-of-mouth and Google. The idea came about when I wanted to post to Instagram, but the API didn't allow it…
Why do you use phones for that? Couldn't you do the same through headless browser sessions?
A low-cost social media posting service is intriguing.