I also use Godot :) I've made the example videos for all of my assets in Godot as well. The canvas size is 160 x 90 pixels, and when you make it full-screen it's nice and big. If you're making a game I'd recommend a slightly bigger screen size, perhaps 320 x 180 to give the cat some space and to fit the widest range of high resolutions, but that's entirely up to you and depends on what type of game you want to make.
Oh, and check this short video out to see how to fix your blurry sprites. It explains it all pretty well, but if you need more information I'd suggest just googling about it and see what comes up. There are a lot of vidoes and info about this and all other things about Godot out there.