But interestingly, the use of minimal viable firmware in the gadget willn't restrict users? What's it like?
And why it will be available only to the owners of the ETH, this will significantly reduce the number of users? Not to mention its cost.

I think that the level of security of the modern messenger is still insufficient. But on the other hand - what should I hide? from whom? and for what? If anyone wants, he will know everything that is needed without problems. For those who don't want to know about this, you need to completely abandon the gadgets. Everyone makes a choice on their own.