I do wonder if that Mac Mini from 2011 I have but haven't used in a long time also secretly supports 16 GB. I upgraded it to 8 GB ages ago and the docs said that's as far as it goes.
(Had to crack it open because the old spinning-rust hard drive was starting to go bad, so I replaced it with an SSD, and figured I should upgrade the RAM while I had it open. I have Linux installed on it, and it's a nice media server box, running Jellyfin and a few other things. Only downside is that its support for HW video decode/encode is kinda limited -- no h265 -- due to its age.)