There are a bunch of places in Silicon Valley. For example: https://www.abettersource.com/ Search for used office furniture.

There are also auctions when a company closes down: For example: https://svdisposition.com/auctions These may include furniture, computer equipment, machinery, lab equipment. Bidding may be on single items or many items batched together, like 50 office chairs.

There was a local auction two days ago (May 16, 2024) for the entire contents of a Red Lobster restaurant that suddenly closed, as one bid.