Switching from a smartphone to a dumbphone is usually not about increasing privacy in the first place.
People tend to make the switch for mental health reasons, rather than privacy ones. When your phone goes back to being a direct communication tool rather than a passtime, you tend to realize just how much time you spend during a day doing basically nothing.
That’s pretty much it exactly. Yubico has the required features, are widely supported, and are widely used. They have a track record of reliability.
Other viable alternatives definitely exist, but they don’t have the same real-world penetration. The disadvantage with that is if you run into a platform-specific issue, finding someone who has had the same issue before and posted the solution somewhere becomes far less likely.