I keep doing more multi-architecture builds using buildx and continue to find good information out there to help refine the process. Here is a post I found I thought I’d share that discusses how to build multi-architecture using AWS Graviton2 based instances which are ARM based. https://www.smartling.com/resources/product/building-multi-architecture-docker-images-on-arm-64-bit-aws-graviton2/. I haven’t officially tried this yet but the same process should also work on a Pi4 with the 64bit PiOS installed.