I share with you one sketch i did, more focused in brush behavior than final result.
I am recently Ipad user and your app is there too which i think is a good idea because i test features when i rest after work in ipad and then paint on Desktop. I have purchased one license. 20e is fine for me as an average price for and app but at least i would like to being able to use also in my laptop . I own Clip studio paint and his license gives me rights to use in both devices.
Anyway i have to say you are doing an impressive job to be only one developer. Only one thing. We as users don`t know which is the roadmap for Paintstorm. Maybe a video would be useful or just a pdf or note.
Also i noticed with ipad that i have always a message of memory warning " only 20mb left" but the app still working. is the Lite release and this detail doesn't convince me to purchase the ipad release.
Have a nice day