So many people seem to have it off and not know it.
I don’t think there’s any mean to know it programmatically, unfortunately.
Consider checking the FPS for a couple of seconds. If the FPS is too low, you could notify the user that they might want to check if hardware acceleration is enabled in order to optimize GPU usage
That sounds like a fair solution. On the other, if it’s for biz and considering the different default settings of browsers and then, the various browser configs set by IT in a business environment, what I usually recommend is to give some information to the user about how to configure the browser (or ask IT to make the config update).