I tested it and worked in most cases. It is not working for n=1 and 3 in the code below:

#it works for n=2, 4, 5 and 6 and 7

but it does not work for n=1 and 3

n = 7 # Minimum number of bits to represent the numbers, n<8
x = randint(low=0, high=2**n, size=100, dtype=np.uint8)
compressed = compact_bytes(x, n)
filename = "compressed.bin"
compressed.tofile(filename)
uncompressed = decompact_bytes(compressed, n)
filename = "uncompressed.bin"
uncompressed.tofile(filename)
uncompressed2 = np.fromfile(filename, dtype=np.uint8, count=-1)