I never used Docker Swarm (so can't compare), but I don't fully understand your point about Kubernetes cloud lock-in. Certainly there are important differences in networking, load balancing, persistent volumes, and other cloud features, but that's not something any platform can just hide/eliminate (e.g. think about AWS ELB/ALB/NLB vs Google Load Balancer). The Kubernetes concepts (Deployment, Ingress, Service) still work mostly the same for the user across clouds. Some other details like non-standardized Ingress annotations are obviously due to not having them agreed in Kubernetes core API (nginx ingress supports other annotations than say Google LB or Skipper).