I really wanted a wheel controller for my truck too, but I ended up learning to "drive stick" because I needed 16 channels.
The transmitter is what determines how many channels are transmitted through the air. The receiver is what determines how many channels are put out through wired connections to servos and other things. With the old standard PWM servo outputs that usually limits the channels, because there is only so much room on the receiver for connectors. With bus protocols like SBUS or iBUS the receiver only needs one physical connection to output multiple channels. You still need a transmitter with 8 channels and an 8 channel receiver that supports SBUS if you want to output 8 SBUS channels over one connection. Often you'll find SBUS receivers with 3 standard servo connectors + an SBUS connector for the whole set of 8 or 16 channels.
The ESP32 soundkit supports a max of 6 separate PWM connections, but more for a bus connection. Plugging in a single bus connection is easier both for the hardware and software parts.
It looks like the standard setup for for the soundkit used 8 channels, but most functions are available with 6 PWM channels. The standard setup is using:
- 2 normal channels for steering and throttle,
- 3 channels with 3 positions (up-neutral-down) for gear, indicators, headlights and engine on/off,
- and a normal channel /potentiometer for horn/bluelight/siren. It seems this one has 4 positions: horn-nothing-bluelight-siren. Skipping separate bluelight/siren controls you should be able to do that one with a 3 pos switch instead, or 2 pos for only horn.
2 of the 3 position channels requires dual rates.
You could probably cut one of the 3 pos channels by enabling auto indicators when turning. If you want to skip light controls entirely and only use engine sound, you might be able to get away with 3 channels (steering, throttle and gear).
I have only barely looked at the Flysky Noble. If it can output 8 channels over iBUS it seems like a good choice. Check that the channels are assigned to switches that makes sense with the info above, and that they have adjustable endpoints.
diyguy also has an open source arduino based pistol grip/wheel controller project that works directly with the soundkit, if you're feeling brave.
Please keep in mind that the above info is strictly theoretical from the documentation and code, and that I haven't tested it. I branched off at version 4, and had to make my own code to read SBUS, simulate an automatic transmission with a separate reverse switch and control sounds directly. I don't use the light features and I don't use any of the standard channel inputs.