Option 1 seems to be logical, but there are other nice fields besides repository like version, homepage, license, and people fields: author, contributors
Option 2 (arbitrary html) also nice to have but probably we may create a Feature request to see the demand for it.
The big problem is where to find the installed extension after a teaching popup was closed. Probably there could be another button near “UnInstall” button, for example “Show” button which would call teachingMoment.
Also, would be great to have different colors for “Install” and “Uninstall” buttons.
I am still getting used to the Inspector v2 code, so better you make this change 