That was a custom built "local controller" that I used in the very first concepts of the solenoid idea. Back then, I did not yet have programmable TX and telemetry and stuff, and the idea was to hook up a stand-alone unit in the throttle servo lead with an on board storage for a fuel curve. That system was intended for a helicopter with autonomous RPM control (governor) so a throttle or pitch based system would not work, it HAD to be an on-board stored curve acting on the governor-output.

That system never came off the ground, since the biggest issue was the user interface, and the (im)possibility to ground-test a fuel curve intended for flight, since running conditions are not th same in a heli.

The controller was a box that allowed to control the throttle servo with the knob, and program a curve that would simultaneously drive the solenoid. I used it to run a glow engine, found that it was at least somewhat possible, then marriage got in the way and the idea was shelved. After my wife died, I kinda fell into a dark pit and picking up the idea was a way to get out of that dark place.

Full disclosure:
This is one of the first tests with forced fuel mixture.
What you see is a (very old and worn) Veco 19, running glow. Needle valve is removed, and fuel supply is forced by a manually controlled positive displacement pump (kinda like a dosing pump). It was sheer horror to get the engine started (forced feed, so the fuel would flow regardless of whether the engine ran or not, flooding was very difficult to prevent). Since engine RPM (and thus carb vacuum) had zero effect on the fuel flow per minute of time, stability could not be achieved, or only extremely difficult maintained manually.

Sinc pumping did not work, I had a look at the solenoid.
The bucket video you have seen.

I then ran the engine. I did maybe 20 or 30 testruns, of which the first 3 were documented, but then progress stopped, and the principle stranded (gasoline was not yet on the horizon back then):
In this first test, I was manually controlling throttle, and separately controlling the fuel feed, in order to get a feel for what was needed. It became fairly quickly clear that the fuel flow was in part manually controlled, but ALSO affected by RPM (carb vacuum) and basically with this set-up it was fairly easy to achieve a stable run, be that rich or lean, and controlling the engine on a constant throttle setting was no harder than setting a conventional needle.
Come to think of it, It was actually during THIS particular run, that I discovered the atomizing effect of the modulating solenoid, because the Perry carbs allow a good visual on the fuel exiting the spraybar. Funny how those memories return...

In this second tst, the throttle servo was also hooked up, and a single knob controlled both servo and fuel feed. Setting a curve turned out to be fairly doable, but it is clear that all the linkages were very sloppy, and results not really consistent

third test, by now I started to overthink how to implement this in a practical model, and ran into the issue of the human-machine interface... How to do that sitting next to a running helicopter? some sort of handheld terminal to change curves on the fly was needed, some form of graphic rpresentation was needed, etc etc, and my then TX did not have that...
That was before the gasoline days.
Then I took to gasoline and planes, and I first messed a bit with modifying existing glow carbs.
Only after buying a Taranis, suddenly I realized that this transmitter basically allready had everything I needed to finish this project as standard options...
All I needed was a different, much simpler driver. But gasoline turned out to be a MUCH broader subject than glow/methanol...