Thanks Chainik.
Sounds like the 15w CPU would only be enough if it could run in boost consistently, which it wouldn't be able to do.
The Mac isn't a bad suggestion, but I think I'd rather just go up in size a bit, and look for something with adequate cooling and a 28 or 35w CPU.
I like to use this scatter plot from PassMark to get an idea of performance per watt. https://www.cpubenchmark.net/power_perf … catter-cpu
I'm thinking anything above ~20,000 on PassMark would do well enough for me. Maybe I can find a deal on something with a Ryzen GE or Intel T CPU. (or build one myself)