This can be done if You strip 24 bytes from beginning.
So file have then packed file signature: 5D 00 00 80
All files have 24 byte extra header where from first:
4 is file crc32
4 is some file type? Packed app has 03 00 00 00, packed gui stuff have 01, other have 00 00 00 00
4 is file lenght
4 is AA 55 55 AA (something spezial ?)
4 is Firmware version FB 7E 3D 00 -> 4030203
4 is buffer 00 00 00 00 (or for future use...?)
We can skip those headers if we cut GEL after them adding 24 to file start addresses.
h = int('280', 16) + 24 <----------- here
i = h + int('10A814', 16)
out = b[h:i]
open('sys/SparrowAPP.out', 'wb').write(out)