cc @Rogdham

For what it's worth, bz2 and lzma's decompressor subclassing fail on creation:

>>> import bz2
>>> class D(bz2.BZ2Decompressor): pass
... 
Traceback (most recent call last):
  File "<python-input-18>", line 1, in <module>
    class D(bz2.BZ2Decompressor): pass
TypeError: type '_bz2.BZ2Decompressor' is not an acceptable base type

>>> import lzma
>>> class D(lzma.LZMADecompressor): pass
... 
Traceback (most recent call last):
  File "<python-input-19>", line 1, in <module>
    class D(lzma.LZMADecompressor): pass
TypeError: type '_lzma.LZMADecompressor' is not an acceptable base type

• Issue: Implement PEP 784 - Adding Zstandard to the Python standard library #132983