> ... it seems I managed to avoid both.

Unfortunately I don't think you'll know for sure if you got sick for at least a few more days. For COVID-19, I think there is a 5-7 day period where you can show no symptoms (but still pass it on to other people.) And even for the regular cold/flu, it can take a couple days for symptoms to show up.

I agree with everything else you said though; wash your hands often, use hand sanitizer, bring lysol/clorox wipes with you and wipe down any shared surfaces if possible.