Can LM verify a server's time is correct?

For Windows, LM does have a built-in check which will "Shows the time offset of the monitored Windows Server relative to the collector" and can cover you here.

For other devices I do see NTP checks but they look to be more specific for NTP servers than clients.

I don't see a specific Linux time check. I'm not sure if it's because we are really only using snmp for Linux monitoring (vs say ssh), but it doesn't sounds like a big deal to add that monitoring if you are familiar with scripting.