That's basically what we've done with https://safepass.me/ and https://pwncheck.me/ ... and HIBP is the dataset we ship to our customers by default. If you are still looking to validate passwords when they're set, give me a nudge :)

We don't advertise the linux/PAM support since we have failed to find a market for it (usually things end up being hooked up onto AD one way or the other)...