Accelerometers measure acceleration. This can be used to calculate the groundspeed of the aircraft. Groundspeed is different than airspeed. For example, if a drone was hovering in a 5mph wind, its groundspeed is 0 and its airspeed is 5mph.

I was a flight instructor for a few years, and have taught many students how to do dead reckoning. That doesn’t mean I’m right, but hopefully gives me enough credibility that you’ll consider my argument. Each of the Wikipedia articles for these topics is robust if you’d like more detail.