Aliexpress has some good mini-PCs based on mobile CPUs. It's been a while since I went shopping for one, so I'm not sure where they are, right now. Since these are typically <=15W parts, they can be passively cooled. Most are fanless, from what I've seen.

I run OpenBSD on an i5-5200U I picked up a few years ago (probably 2015, or early 2016). It serves as my router and runs a bunch of services for me. It lives in my basement next to the fiber line coming in from the road.

I wouldn't be surprised if an AMD -H part comes to market soon in this category.