The nginx ingress controller for example, under the hood, just generates and applies a big ol' nginx config! You can extract it and view it yourself, or extend it with a Lua script if you want to be fancy and do some FFI inline with processing the request, etc.
I learned the hard way that GKE, in using GCP's load balancers don't support the same syntax for Ingress patterns as when you use an nginx Ingress. Definitely read the documentation thoroughly!
Lots of people have different definitions of 'easy' which is why I didn't say 'easy'. But how did you get this far off the rails with 'dead simple'?
Beyond that there's a sea of options for more native integrations that will depend on whether your LB vendor has an K8s integration, how friendly your networking team is, and how much code you're willing to write.
Load balancing should be a solved problem already. Swarm and Kubernetes should be using dead simple off-the-shelf software for ingress and load balancing. Any competitor should be able to use the same solutions. To put it another way, this shouldn't be a differentiator.
The problem is that the functionality in tools like nginx are still tied to static network architectures that evolve slowly, and don't take advantage of things like diurnal variability in workloads.