@emmykei
I tried this, and it ~kind of~ works for what I want. But I have no way of scaling the preview itself.

Consider Aseprite (picture attached). The preview obviously isn't pixel-per-pixel, and it's scaled up using nearest-neighbor to avoid blurring the picture (pixel art usually needs special treatment when resizing). This is much more accurate depiction of what it will look like finished bc with pixel art you generally resize it to retain the pixely feeling on high DPI screens.