ASRock recently announced two new small form factor (SFF) desktop PCs. The Jupiter H310 and Jupiter Q370 both measure just over a litre in volume but can support up to a 65 Watt CPU on the LGA1151 socket. Upgrade options are also quite robust.
https://www.notebookcheck.net/ASRock-announces-new-Jupiter-SFF-desktops-with-65-W-Coffee-Lake-CPUs.333212.0.html
One tiny fan for 65W CPU? Hmm...
These things are going to throttle so bad. That's a single laptop-sized fan on a 65 Watt CPU. GG, ASRock.