The AV1 implementation you have only works on Intel CPUs. For those of us with AMD CPUs, the AV1 option does not appear in the list. Which is why you should expect people to ask for AV1 encoding in the future, as well, until you add an implementation which uses the CPU itself, and the iGPU from AMD, as well as implementations which use the dedicated GPUs (dGPU) form AMD, Nvidia, and Intel.