TLDR; 
I'd like to see quicksync HW decode support in Haruna.
MPV already supports quicksync hw decode, so believe it's just passing some parameters.

mpv --vd=help | grep qsv
    h264_qsv (h264) - H264 video (Intel Quick Sync Video acceleration)
    hevc_qsv (hevc) - HEVC video (Intel Quick Sync Video acceleration)
    mpeg2_qsv (mpeg2video) - MPEG2VIDEO video (Intel Quick Sync Video acceleration)
    vc1_qsv (vc1) - VC1 video (Intel Quick Sync Video acceleration)
    av1_qsv (av1) - AV1 video (Intel Quick Sync Video acceleration)
    mjpeg_qsv (mjpeg) - MJPEG video (Intel Quick Sync Video acceleration)
    vp8_qsv (vp8) - VP8 video (Intel Quick Sync Video acceleration)
    vp9_qsv (vp9) - VP9 video (Intel Quick Sync Video acceleration)

I like Haruna very much. When playing h264 videos with the VAAPI decode, the CPU consumption is somewhat over bare MPV with the same file being played 'mpv --hwdec=vaapi the_file.mp4'
So bare mpv is slightly faster, but obviously it does not have the GUI overhead. 
But playing that file using qsv, the decoding is even more fast in MPV.
I'd expect Haruna being somewhat more efficient with qsv enabled, where possible.

When playing an mpeg2 file, the difference is huge, like night and day.
Moonplayer is simple enough and found the way to implement in my fork:
https://github.com/kovacslt/moonplayer/blob/develop/src/mpvObject.cpp
See there: 
 m_mpv.set_option("vd","h264_qsv,hevc_qsv,mpeg2_qsv,mjpeg_qsv,vp8_qsv,vp9_qsv,vc1_qsv,av1_qsv");
That works like a charm.
However, I like Haruna better, and would like to use it, but I don't seem to find the way to make a similar change to it.
May I ask for some help, or would you be so kind please to implement qsv support in Haruna, and apply hwdecode to all possible content formats (mpeg2, vp9, etc)?
Thank you very much in advance.