Use Nijika for queueing up multiple encoding tasks.
I recommend using a very recent version of ffmpeg and libaom-av1. My recommendation is to use the versions provided in Alpine Linux Edge. Install ffmpeg together with Python in a Docker container, so your actual host system doesn't matter. Here's a possible Dockerfile:
FROM alpine:edge
RUN apk add --no-cache ffmpeg python3
RUN python3 -m ensurepip
RUN pip3 install --no-cache --upgrade pip setuptools pyyaml
Now, create a wrapper script for executing a command inside a container created from this image. It may look something like this:
#!/bin/sh
docker run --rm --net=none --mount=type=bind,source=/home/me/Movies,destination=/ay --workdir=/ay hav1w-env $@
Place the hav1w script together with the presets and the command queue of Nijika inside the directory mounted into the Docker container. Then add a command like this to the queue:
sh wrap.sh python3 hav1w.py input.mkv output.mkv 5.1
Neither this setup, nor this "guide" is perfect. But maybe it helps to get a good starting point :)