I've just launched my netbooting workshop for Raspberry Pi. It was previously only available to sponsors.
The new version includes a PDF, scripts and a community Slack channel as part of the package.
You'll: setup your server with NFS and TFTP, configure filesystems for each of the RPis, get them booting up, measure the speed, then setup K3s in a HA configuration. From there you can learn what to deploy on the cluster, and find a few jump off points for going further.
Hope you enjoy it, and if you're a k3sup.dev user, thank you for the support!