7th gen i5 NUCs can be found on eBay for under $100 shipped with 16gb of ram and a small m2 drive. They’re not as powerful as a larger SFF chip, but at 15w TDP is pretty hard to beat. I have four of them now. I pick one up every time a find a good deal.

8th gens are still really expensive.

For that workload, I’d use an ip can and offload the smarts to something like frigate running alongside the rest of my home automation stack. For smaller workloads it’s esp8266/32 all day long. Again, offloading the hard work to my home automation stack rubbing on decent hardware.