Transcoding anything >720p is painful.
I run ancient hardware for desktop/laptop >10yrs old apple stuff running linux. I consume media mainly via rpi4 or android.
What’s a minimum level system capable of trans-coding 4k video to x265 in at the very least real time? Is there a tiny trans-coding device out there somewhere?
Would a NUC do? How old or new to churn out 4k x265
Can I avoid hardware? Are cloud gpu’s a thing?
Sorry, you need hardware.
If you are doing a ton of encoding, you could even get specialized hardware like amd alevo (spelling?) card which enables you to encode even AV1.
That being said, what are you doing that requires you to encode h.265 on ancient hardware?