Question Output resolution/ setting resolution of the main preview window

I'm mostly creating shaders for pixel art and they come out fine when applied to the actual pixel art, but they look very odd in the main preview because it's rendered in screen space resolution which is much higher than what the pixel art is rendered at:

As you can imagine, those circles are supposed to cut out indivdual pixels at the textures original resolution. Also, the same thing probably happens if you render upscaled pixel art in the application (as opposed to rendering it at original resolution or rendering it to low res to a render target and upscaling that, like I'm doing at the moment).

Is there a way to make the shader adapt to the texture's resolution, or at least lower the resolution of the preview window?

You can try the material out yourself, it's attached as a UnityPackage.