not quite what you're asking for, but mostly to satisfy my own curiosity here's the employers of the top 35, pulled from either the postgresql contributor list or linkedin
Edit: And if looking for 2020, I believe Zenith labs was only founded a few months ago. At the time Heikki was at was vmware, Peter G. was Crunchy Data. And probably half of the EDB ones were 2nd Quadrant including Peter E., Alvarro H. and Vik F. (I think).
https://gist.github.com/lfittl/2f112698f908d38f43f4f2aeaaa94...
Note that some of the folks on the list have changed jobs in the last 2 years, so it wouldn't be accurate to attribute all contributions to the current employer (plus some folks contribute on their own time).
Also, the EDB / 2ndquadrant acquisition has led to a lot of EDB-attributed contributions, which hopefully will last :)
Edit: FWIW, I think your 2020 list has Tom Lane working for Google - thats not accurate (I think you got the wrong one from LinkedIn), as he is still employed by Crunchy Data (since leaving Salesforce in 2015), to my knowledge.
In fairness, I didn't find the postgres contributors list until I'd gotten a little further down the list.