The electronic ones which clamp to the headstock are fine on both electric & acoustic as they work through vibrations as well as sound. Gibson now make a guitar with automatic tuning via motorised machine heads. Bit like Mr Musk's self driving car.
I started playing in 1960 at the tender age of 12, and found that I had two built-in tuners, one either side of my head. 555
In 68 I worked in a music shop in Manchester and my first job every morning, after brewing up, was to make sure that 50 or so guitars were in tune, simply by strumming the open strings.