That’s more or less what I’m saying yes, I do like the original film grain look of movies, and often attempts to remove it removed detail, making things look smudgy.

As for if no codec is designed for this, Blu-Rays preserve film grain, often very well, and they use x265. Granted they do this partially by brute force by having a bit rate of 30mbps+, but I’ve found that you can quite easily reduce that but rate to 12mbps and still preserve most film grain reasonably well. Especially if you use h265, the CPU version (NVENC is nowhere near as good with grain).