I absolutely love the Idea of this phone, I want one.
First of nowadays most phone flagships are water and dust proof that is a very amazing, most awesome device-life prolonging thing and you guys should look into making that possible with you phone.
Second as purist you should go all the way. Decentralised services such as Matrix are by for not enough anymore they store data on external servers and leak critical metadata information.
If you would go all the way you would endorse a distributed social network that routes over tor, gnunet or such service. Unfortunately they are mostly still in development (most notably Secushare over gnunet) or quite unusable (retroshare with tor). But I mean you guys are making new stuff so you should definitely look into secure technology of the future and if you guys help advance secushare for example how awesome would that make the world ^^.
Another cool function would be to be able to run a own network over wifi between phones over ad-hoc, just because it is cool or because there might be a network fall out or you want to be free of carriers and only use wlan. This is kind of a personal gimmick I guess XD
Personaly I am curious if localisation service will make only gps active or if GLONASS and Galileo will also be available? And Break the U.S. American dependency.
Well peace out.