Sure quibble about the details. The point is, these are all attempts to make PG more scalable. Around the time these projects got started Foundation looked like abandonware. If it hadn't, it's possible that "how can we have really scalable SQL databases?" might have had Foundation as part of the answer.
Good point. Still, if FDB was high-profile proprietary software during this time it might have inspired an open source clone. Spanner inspired Cockroach and Yugabyte, after all.