How do you use them in a public space, where others are trying to do the same thing ?

You wear the controls to your own wearable computer/smartphone, which might or not be linked to a better one on the environment that can do a lot more for you.

Voice Biometrics?

And who said you'd like for others to hear what you use them for?

Can you point out which specific advancements in the last few years you are talking about?

It's not so much fundamental advances as much as a maturing of tooling and educational resources. The result is a lot of compelling proof-of-concept implementations:

https://sel4.systems/

http://compcert.inria.fr/

https://cakeml.org/

Where are you getting your statistics from?