No, AV1 is used for video, AVIF is an image format based on the same encoder.
I am also very keen to see AVIF export available in Affinity Photo. If supported, it would be the easiest way to author AVIF files currently, and if AVIF HDR image export from 32 bit documents was also supported, not only would it be an awesome timesaver, it would probably increase the adoption of HDR image and video support on the web.
I have spent the last 8 hours building a pipeline to generate HDR AVIF files using a combination of strict input file requirements and command line tools - if this could be replaecd with a simple export dialog, that would be a gamechanger.