Apple Watch this is not — the ultra-sleek Oura Ring Gen3 has taken the idea of a fitness tracker to a stylish level. At first, it looks like you’re wearing, say, a wedding ring or a standard band.

There’s no device quite as synonymous with the bougie wellness crowd as the Oura ring. Since hitting the smart tech market a few years ago, Oura’s smart ring has gained plentiful A-list fans ...