

I’m not denying that major flaw of Signal, in which part, yes exposing your phone number tied to your Signal account basically negates Signal’s security, as well as Signal’s centralized server being proprietary. Nevertheless, when using Matrix, you need to ensure you and everyone you communicate with uses a client that isn’t still using the deprecated libolm cryptography backend (and that it uses vodozemac).
HealthyPi Move is open source (including hardware) and doesn’t send data anywhere (only locally to the app being developed). It’s available for pre-order at this time.