Here's a description of the .msh format on Adobe Photoshop CC 2019, at least of what I've been able to glean.
The format uses run-length encoding to encode the offset coordinates of the mesh cells and compress empty cells along the way.
The format is little endian. The header is 64 bytes. At 0x10 and 0x14 are the mesh width and height, 32-bit integers. At ...
I'm not sure what the 'louie' files are for, but this python script should help reconstruct the images:
# simple scale from [0,0x1f] to [0,0xff]
val = (n<<8)|n
return [scale_up((val>>0)&0x1f), scale_up((val>>5)&0x1f), scale_up((val>>10)&0x1f)]...
The files you linked, whilst all having an NSH extension actually appear to be slightly different archive formats.
Each of these archive file appears to contains a number of graphics shaders compiled to bytecode for the various architectures. The binary formats of these shaders vary significantly between architectures.
A couple have very obvious clues ...
Port I/O works similar to memory I/O, so the low byte (08) will be written to the port 3CE and the high byte (0xFF) to the port 3CF.
Example from Use of bitplanes in mode 12h:
The index port of the Graphics Controller (part of the VGA interface) is at
$3CE. The data port is at (index+1), so $3CF. If we want to write a 4 to index
2, we do: Port[$3CE]:...