Searching for "site:punkt.ch grapheneos" returns results that don't exist anymore. Articles are linked in the thread which supports this as well.

> They repeatedly said they forked it from GrapheneOS in their media interviews and marketing. They didn't keep following along with our improvements and have shifted away from presenting it that way, partly because we requested it.

And that also matches what is claimed here, they used to market based on this, they don't anymore.