How to find a local flatpak in the Software center?

I’m adding an AppData file to a software project and before submitting a PR I want to see how the application will look like in the GNOME software center.

I may miss some obvious ways to do so, but so far I came up with this. As I’m also working on writing the flatpak manifest of the application, I’ve created a local flatpak repository:

flatpak remote-add local file:///home/fede/flatpak/local

then I’ve exported there the application (built from my fork containing the appdata file):

flatpak-builder --force-clean --repo=local _build org.frescobaldi.Frescobaldi.yml

I would expect that I can search and install the application using either Software or flatpak, but it doesn’t work. Error when I try the installation:

$ flatpak install org.frescobaldi.Frescobaldi
Looking for matches…
F: An error was encountered searching remote ‘local’ for ‘org.frescobaldi.Frescobaldi’: Unable to load summary from remote local: GPG verification enabled, but no summary found (check that the configured URL in remote config is correct)
error: No remote refs found similar to ‘org.frescobaldi.Frescobaldi’

What I’m missing?

Ooops, I misread flatpak documentation.

It seems that flatpak-builder is not aware of existing remote names and --repo should take the full path to the directory, as in --repo=/home/fede/flatpak/local.

Anyway, even after exporting correctly the app, still it cannot be searched nor installed.