I have a simple oscilloscope routine that I added and modified to the Teeny Audio Waveform modulated example program.

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Here is the code:

This Modified Waveform Modulation Example was done on the Teensy 4.1 with a ILI9488 TFT display.
The output is also sent to a PT8211 D/A chip in differential mode.
The original unmodified code is at:
File > Examples > Audio > Synthesis > WaveformsModulated