Debian is getting ready to implement this, for Debian 12 (“bookworm”). This will carry into Ubuntu 23.04 (“lunar”) too.
python-pip version 23.0+dfsg-1 includes PEP668 support, upstream. This version warns users (who have apt-listchanges enabled) about the feature.
python3.11 version 3.11.2-1 or 3.11.1-3 (depending on timing) will declare itself to be EXTERNALLY-MANAGED. This version will carry a README explaining the situation.
We are already hearing from concerned users, whose workflows are going to get broken. I’m expecting some more of this. I wish it wasn’t right before our freeze in Debian, but that’s the timing that this worked out at. If necessary, we can roll back EXTERNALLY-MANAGED in our python3.11 for bookworm’s release, but I’d like to make this happen…