seanBeen running K3s on four RK1 compute modules plugged into a TuringPi2 board for almost two weeks now. Everything except media stuff has been moved over, including this Mastodon instance.
It's been working a lot better than when I had previously tried RaspberyPis. Being able to use NVME storage (I'm using Longhorn) is a huge improvement to the RPi’s USB.