You'll need to learn a lot more about kubernetes to decide fully if you want to do it. I'm more or less telling you that yes there are ways to keep it highly available, but they're going to be literally 10x if not more the amount of effort to spin up and probably maintain.

Proxmox has their own flavor of HA that is a lower level of virtualization. They'll be able to failover a specific VM/CT to another node if one fails, but again pros and cons. The major annoyance for both is where do you put your data so 2 separate nodes can access it? Both k8s and proxmox have different approaches.