Wow, yes, that's pretty much what I wanted GUI-wise. I know it's just static info with links... but if could it could be dynamic, the ideal GUI would disable the 3 sketch buttons until the key is created. And perhaps it would disable itself when a non-Teensy board get selected.
I did run into a possible issue with the IDE. At first it didn't work at all on Linux. But then I tried on MacOS and it worked great. I captured the console messages (easy with Linux) and saw this:
2024-10-13T07:52:47.849Z root INFO [teensysecurity-0.0.1.vsix]: trying to decompress into "/tmp/vscode-unpacked/teensysecurity-0.0.1.vsix"...
2024-10-13T07:52:47.855Z root INFO [teensysecurity-0.0.1.vsix]: already found
2024-10-13T07:52:47.858Z root INFO [teensysecurity-0.0.1.vsix]: already copied.
Sure enough, when I looked in /tmp/vscode-unpacked/ it has the prior copy of the .vsix content (vsix appears to just be a renamed .zip file).
So even though I put a new version of teensysecurity-0.0.1.vsix into my .arduinoIDE/plugins folder, Arduino IDE keeps using the previous copy even after I restart the IDE.