@mikemcg I don't have a T-RGB to use, but I'll try to help.
But, most LilyGO boards' hardest to compile sketch is the factory.ino!
I can compile the GFX.ino for the T-RGB with no problems.
You might try a simple generic Serial.print test program to debug your rig.
I am using:
-Arduino IDE 2.2.1 , but 1.8.19 is fine but you must update all libraries
-ESP 2.0.11 (Board definition)
-I used Github to down load (clone) the complete set of files.
You really should copy all of the files (from the downloaded repository) folder marked Lib into your 'libraries' folder, overwriting and replacing the originals, but don't do a Arduino library update after that! LilyGO boards are very fussy about using THEIR versions of some standard libraries, not good form, tho'.
-All my libraries are current, except the aforementioned LilyGO supplied set.
-and the comm setup is:
"ESP32S3 Dev Module"
Upload Speed: "921600"
USB Mode: "Hardware CDC and JAG"
USB CDC On Boot: "Enabled"
USB Firmware MSC On Boot: "Disabled"
USB DFU On Boot: "Disabled"
Upload Mode: "UARTO / Hardware CDC"
CPU Frequency: "240MHz (WiFi)"
Flash Mode: "QIO 80MHz"
Flash Size: "16MB (128Mb)"
Partition Scheme: "Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS)"
Core Debug Level: "F' PSRAM: "OPI PSRAM"
Arduino Runs On: "Core 1"
Events Run On: "Core 1"
Hope that helps -Terry