https://github.com/sedovalx/openssl-scripts
spiffe://example.org/ns/vkv/sa/nginx --> This is the spiffe id of sample nginx workload pod.
k -n spire-server exec -it spire-server-0 -- spire-server x509 mint -output pretty -spiffeID spiffe://example.org/ns/vkv/sa/nginx
CN name can be anything and need not to be a FQDN. In this helm values, the names are same as certificate like country, CN etc..
cat cert2.pem cert1.pem root.pem > cert2-chain.pem