Yes they do. Thank you, answered my question.
They act as a breaker in order to not lose two spaces in the panel.
That makes good sense.
Are they functional as surge suppression if HO or others turn off breaker for circuit service or other reasons? It seems to me that it would nullify it ability to meet the new code requirement for whole house surge protection if shutting down breaker turns off surge protection.
That’s a good question I was also curious of that but failed to ask.
It connects to the bus bar and is active whether the breaker is on or not. You don't even have to have a load on the breaker, it's for convenience so you don't waste panel space. Of course you would have to pick a load that matches the ampacity of the breaker part of the device.
