True wireless bone conduction earphones are interesting products and could be ideal in some situations like biking and jogging. While they let your ears uncovered, they deliver sound through vibrations along your cheekbones. Bone conductions TWS are not only for those with a mild hearing loss (who'd like to enjoy music on the go) but also they are designed for people who don't like earbuds that jam into their ear canals. They also let you be aware of the surrounding while deliver reasonable sound quality and quality voice calls.
This type of earbuds IMO is an experimental product, but it seems they are well received by users.