You may be conflating programs running in a terminal and the terminal itself. We've managed to get this far without the latter.
Warp could certainly promise not to include any phone-home functionality in their code, but unless it's open-source and everything is audited, it could easily call the host system's HTTP client and still phone home.
Is this true? This sounds wrong to me but I don't know the inner workings of terminals. The terminal just executes programs and handles pipes it seems. A terminal can be completely walled from the internet, and when you execute something from it, say, curl, then curl has it's own memory space and access layer outside the terminal, and just has it's stdio wired to the terminal.
As I said in my comment, even if you "wall" the terminal off from the internet, if it can make system calls on behalf of the user, it can still access the internet.
If a terminal has sufficient access to the host system to call `curl https://www.google.com` on behalf of the user, then it can call it without any user input.
There is nothing on the host machine that can authenticate system calls coming from the terminal application as "user-initiated" or not. This is similar to the warning that "you can't trust the client"[1].
1. https://security.stackexchange.com/questions/105389/dont-tru...
This is a human problem, not a software one. Your terminal is as trustworthy as its creators. It cannot be locked down to prevent telemetry and still be a useful terminal. That was my original point and it is still true.
No one should use a for-profit terminal emulator, especially one created by a VC-backed startup, full stop.