Make sure you have Arduino Nano selected for the board type. The Checkmark/Verify icon should compile the code without uploading it. If that works, then your issue might be related to uploading with the right bootloader. Some nanos require you to select the ‘Old’ bootloader instead of the default one.
Reporting back: compiled correctly this time - I was careful to place the INO in a directory with the specific name exactly as it is on GitHub
Some of this VooDoo I insist is quirky goings on within my Laptop and Windows 11 because things in Arduino IDE application and Arduino NANO hardware do NOT behave consistently session to session. So NOT YOUR PROBLEM.
As it stands currently I have a successful upload now so I’m going to go play with it.
When working with other people’s code I have found it useful to code on a fresh virtual machine I dedicate to that one build or board. It’s overkill but makes debugging a lot simpler.
I wonder if someone will correct the BOM, had to make another order with Thonk for another proxy switch, most inconvenient, and totally unnecessary. Boo Hoo.