This is amazing, Thank you! I'll be sure to let you know if I encounter a more expeditious bumper removal

Two others things:
Have you looked into finding the rear logo lamp part numbers that come on the '23 ID.4's? That is something I hope would be an easy install.
Secondly, have you explored how to unlock cascading, dynamic, sweeping turn indicators?
Great stuff! outside of the mechanical (bumper removal) there is one more "unknown" that is the coding itself. Did connect the light per GTX wiring (connects to the headlight), but the coding is needed...I did some more digging into the LED drivers in the headlight to get more clues, but did not have more time to spend on it. If anyone has more clues - please share.
1) Rear logo lamp. I did not look into the OEM part yet, and I agree there is something "missing" in the rear bar. IMHO the 2023 logo is part of the tail-light, and it is connected inside of the tail-light. But I could be wrong. We need to debug this. Anyone willing to remove the rear middle tail-light from 2023 and share a photo, please? (More background: the middle light has "dry" power connectors on the side, each side has water insulation around the connector, it's not using the "wet" connectors as the outer parts. So any additional "wiring" would need to be done extra careful as you'd need to breach this water insulation...)
2) Cascading indicators - this is about coding. I did not make it work yet. I only got half-way having an empty option in the menu, but not cascading indicators... Any pointers on coding will be appreciated

I'll work over this week on updating my GitHub repo with couple more findings, coding and more detailed wiring on the tail project...
Good luck and looking forward to your findings as you dig deeper!