I would be a little hesitant to get on the ADO bus these days. Pre pandemic, I was a frequent passenger on it. I would spring for a cab this summer. As far as the ferry goes, at least on that you can stay outside and hope for decent weather. If you're outside, keep your distance, and use hand sanitizer after you touch common surfaces, I would guess the risk is fairly low.
It's usually more than 2 hours from the time you leave the CUN airport until you arrive on the island. The bus trip is an hour, the ferry is around 45 minutes, and you can plan on waiting a half hour for each. So that's close to 3 hrs. This summer I would spend the extra money on a direct flight to Coz unless it was basically impossible to do that.
I am planning a July trip to cave dive on the mainland. I'm flying to CUN, and getting a ride from someone I know directly to the house I'm staying in, with the people I'm diving with, so minimal exposure other than the flight. I'm still pretty nervous about it.
One more tip, when you post something asking advice on an internet forum and you get a response you don't like, it's usually best to just ignore it rather than get into it. We've all been guilty of snapping back but it's really not worth it, and it makes the thread less appealing for others who do want to help you.