My current system:

librebooted thinkpad x200 with mic and speaker removed i also use usb sata adapter for hard drive or ssd to not give it (Direct memory access)

Trust level C : hyperbola of cource and learning
Trust level B : im using tox and emails with pgp wen i can
Trust level A : forums, public chats , IRC

Principles:
-- Code should be small in size for verifying. 16 lakh lines of code as in linux is stupid and I can never see it as being secure.
-- Cleaner code which is easy to understand is more precious than concise code.
-- Empty files (like __init__.py which I have to use to create modules in python) should not exist. Finding why they exist is more pain.
-- BIOS, OS should be 100% free software, small such that I can verify it's security problems if I don't trust the coder and hardware must be stateless(absolutely no long term memory, only externally pluggable memory) so that vendor cannot input his malware onto my motherboard.

Trust level C: Private information (Particular configuration of a system is not shared, in general code is shared)

Hardware - stateless (for stateless hardware compilation from code to HDL to bitstream required)
BIOS - small, easy to read code
Kernel and core utilities - small, easy to read code
Applications - Pretty much hyperbola has all free software enlisted.

Trust level B : Option to keep information private must exist (Private means shown only to friends on the network)
GNU Social, Pixelfed, Forums, PeerTube etc

The above option encapsulates trust level A too for me as by default I can choose having public or private posts in my account and additionally having a switch to move the specific post from one to other does the job easy for me.

Obviously, today the Trust level C completely compromises every other thing.

1. Which information should be public? (Seen by adversaries as well as friends)
2. Which information should be shown to friends (in the internet context, to those connected to the network node in a particular service)?
3. Which information should not be shared with anyone?

My question is, design your ideal system and show it.
Constraints:
1. It should only use free software
2. It should more or less be visualizable in terms of today's techonologies (no science fiction)
3. Describe trust levels (like A-public, B-less public, C-neutral , etc.)
4. It should not be difficult for the end user (else practically it will never be implemented)