We branching!

I looked at gpu-screen-recorder

https://git.dec05eba.com/gpu-screen-recorder/tree/src/encoder/video/vaapi.c

it sets

AVHWFramesContext *hw_frame_context = (AVHWFramesContext*)frame_context->data;
    hw_frame_context->width = video_codec_context->width;
    hw_frame_context->height = video_codec_context->height;
    hw_frame_context->sw_format = self->params.color_depth == GSR_COLOR_DEPTH_10_BITS ? AV_PIX_FMT_P010LE : AV_PIX_FMT_NV12;
    hw_frame_context->format = video_codec_context->pix_fmt;
    hw_frame_context->device_ctx = (AVHWDeviceContext*)self->device_ctx->data;

so may be we need to set AV_PIX_FMT_P010LE and not just P010?