I don't know what you did to get yours idling that low. My 800 i5-9500t idles at 9w. I took out the flex io module & wifi card, and make sure nvme has "spin down" but still nowhere near that low.
I had some Acer chromeboxes that would do 4.5w easy without any tuning or setup, and they used pretty low end dyal-core i3's from just barely before the i5-9500t. Generally I don't think servethehome finds many tiny mini-pcs below 7w.
I can attest to coffeeri's consumption, albeit on pure server use-case only. I own a OptiPlex 3080 with an i5-10500T and under default BIOS settings (power states and whatnot), I was very surprised to see a 1.7-2.5w power draw on idle, but under typical desktop use, this becomes 6-8w. If this is your draw under a server deployment as well, unfortunately I don't know of any methods to rectify this personally.
When it has to roar however, the draw is substantial compared to my ODroid, but since it idles the majority of the time, I'll take it.
Have you enabled the deep sleep state in the BIOS?
It always depends what you are running on it. For me it's very light with only paperless-ngx and a smb share on a nixos.
I also only have one RAM stick installed and set up powertop on startup.
I had some Acer chromeboxes that would do 4.5w easy without any tuning or setup, and they used pretty low end dyal-core i3's from just barely before the i5-9500t. Generally I don't think servethehome finds many tiny mini-pcs below 7w.