To clarify some pieces once again, I put up some basic statements or questions:

For an end-user to utilize video acceleration support, he/she need a computer with supported graphical hardware with libs/API and drivers for it(?)

The libs and drivers can be dynamical linked (enabled) to the system or static built (embedded) in CinGG?

So what happened when adding oneVPL (qsv) support to the build system; dynamic linked to system or static added embedded into the build?
If oneVPL was dynamic linked, the qsv support may be be distribution specific, or if static built it will be generic available on compliant hardware?

Is it correct to say the build machine does not need the specific graphical hardware, but needs the actual graphic libs installed to build Cingg with it?

Could in principle similar methods be extended to include broader video acceleration support for AMD/amf and NVIDIA/nvenc?

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So a confusing piece if "oneVPL" instead should have been replaced with "libvpl?, because I just read
Note for Users of Intel® oneAPI Video Processing Library (oneVPL) and for Intel® Media SDK
https://www.intel.com/content/www/us/en/developer/tools/vpl/overview.html

oneVPL is now called the Intel® Video Processing Library (Intel® VPL). The library will no longer be part of the oneAPI specification so that Intel can focus on providing video processing features on Intel GPUs.

In comparision on openSUSE/Slowroll on Intel, there are libvpl(2) (and no oneVPL).
The oneAPI Video Processing Library (oneVPL) provides a single video processing API for encode, decode, and video processing that works across a wide range of accelerators.
ffmpeg similar has --enable-libvpl --enable-vaapi --enable-vdpau --enable-vulkan