> What is your use case that is currently not met?

docker-ce-rootless-extras

from repository:
https://download.docker.com/linux/debian bullseye/stable amd64

Its version 5:20.10.11~3-0~debian-bullseye introduced this requirement:
Package: docker-ce-rootless-extras
Version: 5:20.10.11~3-0~debian-bullseye
Priority: optional
Section: admin
Source: docker-ce
Maintainer: Docker <support@???>
Installed-Size: 20.5 MB
Depends: dbus-user-session, libc6 (>= 2.3.2)
Recommends: slirp4netns (>= 0.4.0)
Conflicts: rootlesskit
Breaks: rootlesskit
Replaces: rootlesskit
Enhances: docker-ce
Homepage: https://docs.docker.com/engine/security/rootless/
Download-Size: 7,912 kB
APT-Sources: https://download.docker.com/linux/debian bullseye/stable
amd64 Packages
Description: Rootless support for Docker.
Use dockerd-rootless.sh to run the daemon.
Use dockerd-rootless-setuptool.sh to setup systemd for
dockerd-rootless.sh .
This package contains RootlessKit, but does not contain VPNKit.
Either VPNKit or slirp4netns (>= 0.4.0) needs to be installed separately.

Bernard (Beer) Rosset
https://rosset.net/