Does Google cloud offer them on a "aws outpost" style model? I think that plus cloud access is probably the easiest and ' best ' way to offer them. Last thing you need to be dealing with is super micro, gigabyte etc building a box for them and so on - I can definitely understand not selling the raw chip.
Also, if they are so good, it's best to not level the playing field by sharing that with your competitors.
Also "chip makers with the best chips" == Nvidia, there aren't many others. And Alphabet does more than just produce TPUs.