Im on board with the size ratio, Im hoping you know what minimum pixel dimensions is needs? Eg: 128x128px
If I do a big painting it would be muddy and hard to see when shrunk small, but if I do bright pixel art it would be blurry if scaled up. If you're not sure I might just do some kind of vector or cartoon.
It will take me a day or three but I'll get something to you :)
