Is anyone using p2p ostree support?

[Alexander Larsson]

I'm at a point where I'm starting to reconsider the support for the
p2p ostree setup in flatpak. We keep running into issues with it,
which means we haven't been able to enable it by default on flathub.
And it vastly complicates the code as well as the behaviour of flatpak
on the network, turning a simple natural workflow into something that
is super-hard to reason about because information comes from several,
partial and untrustworthy sources.

I know endless uses p2p as a way to do sideloading of apps via usb and
external disks. Similarly there has been interest from redhat in
shipping flatpak apps with the OS install media for install/update
during OS install. However, we could still support such use of p2p,
but in a less abstract way.

I imagine we could do a regular flatpak install/update operation with
a manual option to use a different url for a particular remote. This
would move the p2p installation source choice to the
FlatpakTransaction level rather than deep in the guts of ostree pull.
That sounds a lot more supportable.

However, to make sure we're not regressing something I'm interested in
knowing exactly who uses p2p, and how. Rob, could you (or someone else
from endless) write up a short document on exactly how p2p is use at
endless and what future plans for its use you have?