You might misunderstand by the way what Raspberry Pis orginally made for and they might fail for your K8s workload because of it, they are usually way too weak, if you want to use a RPI 4, then I would not say that, because that is pretty powerful, but anything lower will give you a very bad experience indeed. I tried to run a zabbix monitoring server on a RPI 3 and it kept having problems with the MySQL DB because it was just too slow and the kernel not optimized for a database workload like that.
K8s is built for big enterprise, not tiny little maker computer, these systems are on the very extremes of these scales.
Also, you will notice that the SDcards start giving problems, as they are not made for these kind of read / write workloads, I had my RPI 3 fail in a few days, having read / write errors due to that. They recommend to use SSDs attached via USB as the main drive.
I know that people attribute all things to RPIs and they are amazing, but K8s is the workload I would least ever put on a RPI. Just my 2 cents.