What is the name for a hardware equivalent of a Widget?

In graphical UI development, we have buttons, knobs, and sliders and the hypernym would be widgets.

In computer hardware, we have buttons, knobs, and sliders and the hypernym would be ... for some reason it isn't coming to mind.

Is it still a widget if it isn't in a graphical user interface?

I wanted to tag this #hardware but apparently, the local ontologist doesn't believe in the existence of hardware.

It's still a widget. Widget was a general term for a small piece of hardware long before software existed. The term was just incorporated into software terminology.

The same thing thing applies to "bug" which originally applied to a fault in wiring, particularly complicated sensitive wiring like telephone and aircraft systems. The idea was that insects had crawled into the wiring, shorted them out with their bodies and not only killed themselves but caused faults which were difficult to identify. Early computers, being large pieces of complex wiring, suffered from "bugs" and the term passed into software terminology as higher level languages enabled more complex programming.

One word is control, but hardware items tend to have their own specific names, as the Lexico entry demonstrates.

control

1.5 [count noun] A switch or other device by which a device or vehicle is regulated.

She pressed one button and the controls, switches, and buttons all came to life around her.

Most excavator operators find it easier to operate levers, switches, and other controls with their hands or fingers rather than the ball or heel of their foot.

He pressed a control on the device before him.

— Lexico

There isn't one that exactly fits.

Software and Hardware have different nomenclatures because they have opposite problems. The absolute last thing hardware people need is hypernyms. A software widget can be configured after you have it in front of you. Hardware has to be ordered by part number. If you want a Honeywell waterproof toggle switch for your tractor, you have to tell them which of the 1000 or so different PNs, all identical to look at, that you want. Imagine that every implementation of every button, slider, and knob had to be given a separate control number. My catalog of window screen and door screen hardware is 1200 pages. Door hinges and latches - 800 pages.

Having said that, there is a hypernym for a subset of what you ask for - pilot devices