Generators require a __next__ method, yield statement, or generator comprehension. What you've got is lambdas and a list comprehension. Rewriting using generators would look something like:

    items = [1,2,3,4]
    gen1 = (x*2 for x in items)
    gen2 = (x+4 for x in gen1)
    gen3 = (x*1.25 for x in gen2)
    result = list(gen3)

It's nicer in a way, certainly closer to the pipe syntax the commenter your replying to is looking for, but kind of janky to have to name all the intermediate steps.