All the NUCs and other mini PCs I see run mobile processors.
It’s a shame because a simple downdraft air cooler with a 120mm fan can handle a pretty high power load and could definitely fit in a tiny space.
Add a few thunderbolt ports and you could have a capable and upgradeable little pc.
I’m not so confident as you in stuffing a 100-150W TDP CPU in a NUC-sized case.