Loading 3D model
Aha, if you click on the texture chosen, you can actually choose nearest neighbor. Originally I thought I couldn’t control bilinear interpolation in Sketchfab, so I cranked up the texture resolution so that it mostly looked like nearest neighbor sampling. I increased each texel to be 4x4 texels. Despite the much larger image size, the RGBA texture, due to compression, goes from 188 KB to 293 KB in size - not terrible.
But now I can get precise nearest neighbor sampling by messing with every texture, individually.
Compare this to https://skfb.ly/Ksu7