....I might use BC's for audio route prompts though.
Here's an example from JL
https://www.johnlewis.com/shokz-openmove-bluetooth-wireless-open-ear-headphones-grey/p110575797
Yes, I thought routing instructions might be one use for cyclists.
I don't know anything about the John Lewis item you refer to, but I wouldn't have thought it would be particularly suitable for a cyclist. Mine have a half-loop over the ear to position them positively (photo in my original post) while the one from JL you illustrate looks like backwards cafe-racer sunglasses that will slide off your ears -- also backwards -- at the first sleeping policeman you ride over. More fashion than kinesthetics...
Also, they seem a bit pricey to me for something you intend to use only for the presence frequency range.
BTW, the ones I bought are more than reasonably water-resistant. Earlier tonight they fell off a stack of watchboxes on which they were balanced for charging and into my lime and honey tea. I rescued them, shook them a bit to get the running liquid off, put the captive rubber plug back in the USB-C charging port after blowing into the port, and tried them with music, and allelujah, they worked fine.