Thanks for sharing! One thing I've thought about for marketing an app like this was to just sit down and do a Twitch stream or something and screen-share while using the app. I feel like if it looks cool enough you'll get a few folks that want to check it out.. and hopefully it snowballs. You could record it and slice up clips for YouTube with the good parts..
And another note.. Free-to-play apps with IAP could benefit from learning about how it works in the gaming industry. I highly recommend the Gamecraft podcast from the incredible VC Mitch Lasky
Good luck with marketing!