Not to one-up you, but I'm doing the same with an Odroid H4+ board (no case yet, although I'll probably 3D-print one), which has the exact same transcoding feature as part of its Core i3-N305. It can handle multiple 4K HDR streams just fine (at least in theory - I'm only serving three users at once at most and none of them are using 4K HDR) - all while being passively cooled and using about three smartphones worth of power. Note that I had to use a dummy HDMI plug in order to get the hardware decoder to kick in, since I am using this as a headless server.

I paid €240 for it new, which is a steal (although you have to get SODIMM DDR5 memory for it, which isn't that cheap). On the official website, it's available for $139, but that's without shipping and import duties from South Korea.

Granted, apart from the transcoding feature, general-purpose performance is not even close to your i7, but I'm using less than half as much power for the same job. If you have an i7-1260P, you're about 70% ahead in synthetic benchmark, but my little i3 is still an 8-core CPU that has about 25% more CPU processing power than an old i7-4790k that I was using on my main PC (including for gaming) until last year. Since I am limited by my storage array going through a single SATA cable anyway, that's fine by me, especially since this thing replaced a significantly less performant Intel Atom-based mini PC I was previously using for the same purpose. My priorities were having multiple SATA ports, being low cost, efficient, quiet and small - and in that order.

People have also used the same board as a normal PC and reasonably capable low-end gaming/emulation machine, by the way. You can get a case that looks like a Nintendo GameCube straight from the manufacturer. Here's an overview video that includes it being used for this purpose.