This evening, I got mine working.
Here’s what I learned:
That 5 conductor wire is not the USB wire. There must be some little board in between the two. But I am only taking out a couple screws and gently prying at the front right area of my unit, so I’m very limited in what I can see and reach.[0]
I had tested for voltage on the 5-pin connector, but couldn’t find any. So I plugged it back together, then I got the expected 5VDC on the outer USB pins.
I then put everything together on a breadboard to test:
After some initial fits and starts[1], I was off to the races!
@topdog360, I have not tried to use the remote yet, but I did also experience some temperature weirdness (in the thermostat in HA web UI). After doing the following, it started working:
climate:
- platform: midea
# was originally:
visual:
min_temperature: 70
max_temperature: 80
# changed to:
visual:
min_temperature: 70°F
max_temperature: 80°F
Now that I’ve proved to myself this works, I will work on miniaturizing it so I can tuck it back away in there nice and tidy (I did not have any ESP-01 on hand, but I will order some; or perhaps the Dudanov boards…).
I am also very seriously considering going out and buying 1 or 2 more of these units for other rooms in the house, and altogether stop using our extremely inefficient central A/C unit(!).
@balloob, If I do that, I should have 1-2 spares I could send you to play with. I’ll let you know.
Now, time for a celebratory cold one (or three)… 
[0] I had come across a pretty good teardown video for the Midea U-Shaped and I did not want to get into all that just yet, as my unit is still brand new.
[1] First I had logging enabled, which conflicted with the UART communication, so I disabled that. But I was still able to get logs via ESPHome wireless API (neat!). Then I realized I needed to flip TX/RX around.