libva error

I tried to make possible to use hardware decoding on my Beelink tvbox with Armbian-20.10 with Ubuntu Bionic version (with kernel 5.9.0) compiled by @balbes150 but this error message occur:

root@arm-64:~# vainfo 
libva info: VA-API version 1.1.0
libva info: va_getDriverName() returns -1
libva info: User requested driver 'vdpau'
libva info: Trying to open /usr/lib/aarch64-linux-gnu/dri/vdpau_drv_video.so
libva info: Found init function __vaDriverInit_1_0
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object file: No such file or directory
libva error: /usr/lib/aarch64-linux-gnu/dri/vdpau_drv_video.so init failed
libva info: va_openDriver() returns -1
vaInitialize failed with error code -1 (unknown libva error),exit

I read a topic Understanding Hardware-Accelerated Video Decoding b

ut I still can't understand:

1. Why libva need VDPAU backend libvdpau_nvidia.so because my Beelink box has Mali-450 GPU?

2. How it's possible to get libvdpau_nvidia.so file? On Ubuntu bionic this file available in packages only for architectures: [amd64] [armhf] [i386] but not for aarch64 (ARM architecture of my Beelink).

3. Maybe need to use exactly some value for LIBVA_DRIVER_NAME environment variable?