This would work by switching back to a greeter that disallows VT switching. A lock API would then allow listing existing sessions, including some means to recheck credentials before switching back to them.
That could be a much needed feature. Do you still have any plan on this ?
It is not currently being worked on, and first requires adding support for multiple parallel sessions on different VTs, which is a larger change.
Understood. And just to be sure, I tried a lot of things, but there is no way to use a DM as a lock screen without closing the session or killing the DE, right ?
As greetd allow to execute any command on login, I tried something like locking the DE on VT1, then run greetd on VT 2 and chvt to it, to unlock the DE on VT1 then chvt to it. But launching greetd on another VT that way lead to a strange behavior when keyboard input was messy. I also tried to launch greetd on an existing X session. But the keyboard was sending no input to it, and no way to change VT/TTY.