The only program I've seen with AV1 NVENC support is ffmpeg. And wow it was nice and fast and high compression. On my 4090 was about 100fps on 4k and 550fps on 1080p AV1 gpu encoding.
But yes I'm with you. Please PLEASE give us gpu AV1 encoding support.
Now all we need is plex to enable AV1 playback. No matter the playback device, plex will NOT play av1 files. transcoding or not.