That Voyager 60+ is interesting, taking a different approach to a solution: if I understand correctly, it essentially turns the charging unit into an Airfly, rather than turning the earbuds into wired units? I guess it would require the earbuds to have some charge remaining.

Agree on wired headphones as backup being a decent option. I keep a set of free earbuds in my travel bag in case I want to charge my over-ear headphones.