This thread is about using multi-machine clusters, and sqlite cannot be used for multi-machine clusters in k3s. etcd is the default when starting k3s in cluster mode [1].
No, this thread is about multiple containers across machines. What you describe is multi-master for the server. You can run multple agents across serveral nodes therefore clustering the container workload across multiple container hosting servers. Multi-master is something different.
The very first paragraph of the first comment you replied to is about multi-master HA. The second sentence in that comment is about “every machine is equal”. k3s with sqlite is awesome, but it cannot do that.
[1] https://docs.k3s.io/datastore