Since there's already some good progress in Rescue Team DX modding, I figured I'd create a thread here. I'll add more things in the future. Please feel free to contribute!
Here are my research notes: https://www.notion.so/RTDX-Research-Notes-2a8a4c046e2c42d39a81a3ad1694171e
Other interesting resources:
https://github.com/evandixon/SkyEditor.RomEditor.Rtdx