Oh, wow! I hope no one accepts an online CPR cert. I teach CPR/AED/First aid and the number of people that need help in doing it correctly is small, but worth every moment spent in class for the person that might need their help one day.
If you already have taken the course several times, you should do the “challenge” or an abbreviated course for recertification. But getting your hands back on a manikin every couple of months (let alone two years) is a good idea. It could save the life of a family member or friend.
You should also check with places that offer professional liability insurance (if you are going solo you will want that) and with places you might wish to work (to see what they require). You do not want to spend money on something that is not going to work rather than getting what you need righ away.
Do you already have a health background? Is this a recertification? If not I would absolutely recommend doing a training that has some hands on work. The latest one I took had a great online piece, but also a few hours of hands on training and questions from the leader to see if we got the information in a practical way. I don’t know of any online only places, but even if I did, and even though I’ve been recertifying for decades, I still would take the one with hands on. This is about being prepared in a life and death situation.
And yes, I know of more than one situation where a fitness professional probably saved a life with this training.