Of course if you deck out a Pi 4 with a SSD and a fan, it'll come much closer to the G3 Mini in terms of power consumption.
When you throw in m.2, lots of ram, all that IO eats power. So the minimum idle power creeps up. Arm boards too.
Not sure about the <=G3 and >=G7, but the G4 and G5 have the issue. The G6 seems to have the fan attached more firmly, but I've never tested one in a quiet room.
Lenovo has M700, M75q (AMD) and a bunch others ranging from thin client to workstation performance.
Generally new ones are awesome at about $700 but older ones are absolutely capable for upgrading ram, disk, wifi whatever. there are modules for up to 10g and other things too. Servethehome on YouTube has a bunch of guides.
If you can get friendly with local electronics recyclers or auction buyers you might do way better.
One was immediately wiped and I installed Debian 12. The other was wiped and I installed Windows 10 Pro. Both seemed to just work.
Hard to beat for less than $200 CAD.
And they advertise up to 3 monitors support.
Unless you need the GPIO or have a pi-specific purpose, used thin clients or tiny PCs make more sense for a home server now IMO.