Using named pipes on Windows?

[Selur]

I use named pipes created by Vapoursynths vspipe (supported since R72), problem is neither: NVEncC, QSVEncC or VCEEncC does support them as input.
(ffmpeg, x264, x265 and other encoders do)
Starting:
"F:\Hybrid\64bit\Vapoursynth\Lib\site-packages\vapoursynth\vspipe.exe" "J:\tmp\2026-07-11@16_20_42_1110\encodingTempSynthSkript_2026-07-11@16_20_42_1110_0.vpy" \\.\pipe\2026-07-11@16_20_42_1110_02_video --outputindex 0 -c y4m
and then
' "F:\Hybrid\64bit\NVEncC.exe" --y4m -i \.\pipe\2026-07-11@16_20_42_1110_02_video --fps 25.000 --codec av1 --sar 1:1 --lookahead 32 --output-depth 10 --vbr 0 --vbr-quality 23.00 --aq --aq-strength 5 --aq-temporal --gop-len 0 --ref 6 --multiref-l0 3 --multiref-l1 3 --bframes 3 --direct auto --bref-mode auto --no-b-adapt --mv-precision Q-pel --preset quality --colorrange limited --colormatrix smpte170m --colorrange limited --cuda-schedule sync --output "J:\tmp\2026-07-11@16_20_42_1110\test_1_2026-07-11@16_20_42_1110_02.av1"'
same for QSVEncC&Co.

All fail with:

y4m: Failed to open file "\\.\pipe\2026-07-11@16_20_42_1110_02_video": Invalid argument.
failed to initialize file reader(s).

Am I doing something wrong here, or does NVEncC&Co not support named pipes. If they do not support it, it would be nice if this could be added.