Are the resistor values for 12 Bit the same for the R2R?
Yes Frank , the resistor value are the same when you add more stage ( 1 x 536 and 1 x 270 ohm ).
Just bad that i cant help for the VGA code on Teensy , i was more involved in STM32 in the past , and the registers / DMA etc used on teensy are actually black magic up i can learn more on this MCU