I forgot to say earlier, but thanks for these links. I've learned from them the magic key words to include in my web searches: "viral persistence" and "cardio myocytes" are a great start.

Not related to my specific idea of sars-cov-2 infection within heart cells, but this Western Australia presentation makes it fairly clear that covid-19 is a lifelong illness for many people.
https://www.youtube.com/watch?v=6UzOav3x8Q0