Vulkan is a low-overhead, cross-platform API, open standard for 3D graphics and computing (Decoding).
Going public back in April was the provisional specification around the Vulkan Video (Decoding) extensions as a new industry-standard video encode/decode interface. While several months have passed, there hasn't been much activity yet in the open-source space around Vulkan Video. As it stands now on Linux there are NVIDIA Vulkan beta driver builds supporting the Vulkan Video extensions but there isn't any support elsewhere whether it be closed or open-source Linux drivers... Sadly, nothing yet from the Mesa Vulkan drivers.
On the upstream Vulkan front, the extensions currently remain provisional and also only tailor to H.264/H.265 with no VP9 or AV1 extensions yet. But for those interested in hearing more about Vulkan Video, Victor Manuel Jáquez Leal of Igalia talked about it during last week's X.Org Developers Conference. His XDC2021 talk was focused on the application/client side from the perspective of the GStreamer multimedia framework for supporting Vulkan. That work in progress code for GStreamer Vulkan H.264 decoding remains pending.
The slides for those interested can be found here and the XDC2021 presentation below. Hopefully when Vulkan Video is declared stable in the months ahead, in 2022 we'll see more open-source adoption around this video API and Mesa driver support.