I assume it doesn't, but thought I'd ask.
I really like the principles behind both gentoo and flatpak, but right now I can only do the gentoo way or the flatpak way (and I've opted for gentoo's for now).
What I'd love to have from flatpak:
- container like sandboxing and isolation
- customizable sandboxing and permissions
What I'd love to have from gentoo:
- powerful build system building packages from source
- global declarative management of compilation options
- easy patches
- easy to add packages that aren't in repos
- support for many architectures or setups
I've seen NixPak which I think would be just what you want, except that it's for Nix instead of Gentoo. But Nix has the same features that you say you like in Gentoo.
Would running gentoo in a distrobox container work for you?
How about not changing at all your regular packages,and containerizing what you want, or as much as possible through current profiles, through firejail? And couplet that with MAC protection offered by apparmor (one can actually set firejail to always use apparmor, and then tweak particular apps not to use it if it's too troublesome).
This way you have your provided distro packages (gentoo or sourcemage if source based distros, it doesn't matter), and have them execute containerized. The only thing is that there are not firejail profiles for every possible piece of SW, but the vanilla list of containers is not small either.
At that point you might as well use a Docker type container in which to build your software from source and deploy in the container.
But Flatpak has its fancy "portals" to connect each app with the specific resource it needs which you don't get with Docker.
Also if the goal is to limit access of apps you don't want to fully trust, I think Docker doesn't have the appropriate security properties. Here's a quote from the readme for Bubblewrap (the sandboxing tool that Flatpak and Nixpak use),
Many container runtime tools like systemd-nspawn, docker, etc. focus on providing infrastructure for system administrators and orchestration tools (e.g. Kubernetes) to run containers.
These tools are not suitable to give to unprivileged users, because it is trivial to turn such access into a fully privileged root shell on the host.
in theory shouldn't it be possible to use bubblewrap and the xdg-desktop-portal project to hack together only the sandboxing bits of flatpak while leaving out ostree/distribution
you might run into this though: https://github.com/flatpak/xdg-desktop-portal/issues/737
Build everything you use in podman or lxc
From my understanding this doesn't work too well for GUIs
Build everything you use and ackage it in flatpak?
It's not even that hard to build your own gentoo-based runtimes and install stuff on top of that. Fedora does offer that, too, offering fatpaks based on their own fedora based runtime + rpms.