Final Fantasy Tactics: The War of the Lions Texture Pack

[LunaMoo]

See PNG as a container for compressed image and even if the image would compress better than texture resulting in smaller size, once it finishes it'll be a full size texture.
Meanwhile ktx2 is a lossy Basis or UASTC compressed texture format, so memory wise it's actually much smaller texture and will load faster.

If you really want to show love and have time to tweak stuff you might consider using lower quality basis ktx2 files (remove "-uastc" when converting to get basis) for textures that aren't in the center of attention as the thing with most textures is they don't need full quality to look very nice, you can also skip "-mipmap" for UI stuff and other textures that doesn't benefit from having mipmaps as it also add's to final texture size.
Finally if you really see a quality difference in something that is really important to look as perfect as you made it and it makes you cringe to see that one or few pixels in slightly different color than you planned, you might consider using zim format. It's much larger file size and the texture size is as with png's - full, but it's still like 3 times faster to load than PNG's.

Personally through I don't think it's worth your time fine tuning especially with ktx2 in UASTC with mipmaps for everything works really nice on it's own even in quite laggy packs.