Are you looking for upscalers?
I've taken Skypiea 1 and upscaled it from 480p to 1080p with these results (4 comparison images):
https://imgur.com/a/f5qBYI2
I've input custom parameters in the upscale, that I think work best with animation.
If there are episodes we never expect to get in higher resolution, this is something I can help with.
-All images are a 225% upscale, comparisons are however just screenshots. First three pictures are shown at 100% zoom Fourth picture (Luffy) is shown at a 200% zoom to better illustrate image quality improvement
-400% zoom example: https://imgur.com/a/Sny0Gfe
-This was done starting with a <100MB file, with pre-export files I would expect even better results
-I would have asked on discord, but I'm having login issues