You upgraded to the modern RPi kernel/firmware stack, as offered with the DietPi update, right? uname -a
Support for the legacy GPIO APIs has been removed. Drop-in replacement for rpi.gpio is indeed rpi-lgpio, which makes use of the modern lgpio library. Indeed we need to replace the install option as well.
gpiod is the other modern GPIO tool, so that Node module seems sane.
pigpio however is another legacy RPi-only library. Is it still required for certain GPIO functionality of Node-RED?