Several of the newer Chromebooks support USB-C charging
Sure, but I'm not looking to get a newer Chromebook; I like this one, because it's tiny.
It turns out that the answer to USB-C charging the C100 Chromebook is to... get a
C101 Chromebook instead.
It's unclear to me whether my Anker 13000 (5v 3A) will charge it, though: the included power supply offers 15v 2.2A. Does USB-C allow that kind of thing?
I suspect (maybe) not, based on
the specs for the Anker 20000 PD which says "some USB-C laptops are not supported as their input exceeds 22W", and the
spec for the C101 says that the PSU outputs 33W, which implies that the Chromebook might
need 33W. However, also on that page, it says "support power delivery".