On my system i was able to use my integrated iGPU wit the follwing:

    devices:     - /dev/dri:/dev/dri

The rest of your compose looks fine.

Isn't your GPU an Nvidia RTX 2060? Why are you trying to use the Intel GPU acceleration method? I'm confused

This is how mine works, with a Nvidia GPU

services:
  jellyfin:
    volumes:
      - jellyfin_config:/config
      - jellyfin_cache:/cache
      - type: tmpfs
        target: /cache/transcodes
        tmpfs:
          size: 8G
      - media:/media
    image: jellyfin/jellyfin:latest
    restart: unless-stopped
    deploy:
      resources:
        reservations:
          devices:
            - driver: nvidia
              device_ids:
                - "0"
              capabilities:
                - gpu

I have an arc for transcoding, and I had to set the device to /dev/dri without the renderD128 part. If I were you, I would just use the 2060. If it's there for llama or something I'd still try it and see how it does doing both at once, as it should be separate parts of the gpu handling that.

If you switch the devices line to

- /dev/dri:/dev/dri

as other have suggested, that should expose the Intel iGPU to your Jellyfin docker container. Presently you're only exposing the Nvidia GPU.

Do you have the Intel drivers installed on your machine? Are GuC and HuC working?

sudo reboot
sudo dmesg | grep i915
sudo cat /sys/kernel/debug/dri/0/gt/uc/guc_info
sudo cat /sys/kernel/debug/dri/0/gt/uc/huc_info

On Debian I had to manually download the i915 full driver Zip, extract it, take out the Intel drivers, and put it in /usr/lib/firmware

Then hardware acceleration worked on my Arc380.

If you use QSV, your CPU iGPU will be the one that can use it, so make sure to set your render device in docker to the iGPU and not the RTX 2060