Hi!
If the app ends up having a big enough audience, we'll surely put it on Steam, and if that happens, all itchio buyers will have a free Steam key like we did with Pixel FX Designer.
About the bigger sprites, I'm planning to do some tests with a bigger canvas, but depending on the size it might be an overkill for most GPUs, so I can't promise anything at the moment, but I'll surely look what it can be done.
Thanks for the support!