Ideal k8s setup for 2 asymmetric machines?

My current setup consist of one beefy machine (18 core 32GB) running a bunch of containers. I recently acquired a NUC and loaded it up with RAM but it's nowhere near as powerful. The large machine runs proxmox but I have yet to setup the nuc. I've been meaning to setup some of my containers on kubernetes for a while now, both for learning and for redundancy. Obviously when the big machine dies, all my services go with it including email which is rather bad. The point is, the NUC can have a much more reliable uptime for... Reasons. I want to be able to have some core services such as email, move over to the NUC in case the main machine dies.

I had in mind, a dual node k3s, both nodes being masters and workers or whatever the combo is so that failover works seamlessly (storage also needs to be redundant between the machines). However I've been reading that etcd needs 3 minimum nodes. So am I better off with 2 virtualized nodes on beefy and one bare metal on NUC or is there another solution I've not found?

What's my best bet setup for this?