This an example on how one could stitch a K8 cluster across Azure, GCP and AWS using Terraform

It is not a PROD ready example - In fact if you are considering a cluster across hyperscalers
strongly consider the reasons why?.

When multi cloud Kubernetes is worth it

It makes sense if
You sell to regulated industries
You need regional survivability across providers
You want leverage in cloud negotiations / costs

It does not make sense if

You are early stage
Your team struggles with one cloud
You think this reduces complexity

bottom line - It increases complexity. Full stop.