There really isn’t an answer to the question.
How does the Snap Store verify attribution and provenance? How is the metadata prepared and provided for each application? Who does the releases and uploads them to the Snap store?
I mean: the Foundation could keep credentials or GPG signatures, but I haven’t see any GNOME application maintainer in that screenshot you provided. Some apps are provided by Canonical—I assume by turning a deb package into a snap one—while others are provided by Ken Vandine.
The GNOME ecosystem seems to have pretty much standardised on two things:
AppStream for application metadata—including project provenance and affiliation
Flatpak and FlatHub for application packaging and distribution
Core GNOME applications are automatically built and pushed to Flathub. Maintainers of core GNOME applications that wish to push their releases to the Snap store have to do so manually; if we wanted to have them appear under the same affiliation, we’d need to either share the account credentials, or we’d have to centralise the role of the person doing the upload.