I've seen exactly one of these in person while in San Diego for a month or so. I never did see a fueling station for it though.

There's only... well, 51 of them. If you're lucky, you're near one of the 42 that are actually online and available for fueling (as of this comment).

Stations running out of fuel and stations going offline for hardware failures runs rampant.

Oh, and some stations might not be able to provide the highest pressure H2, so you might be stuck taking an 85% tank fill... and at nearly $30/kg and a 5.6kg (full) tank, that's an expensive fill.

https://h2-ca.com/