I don’t know that there’s an easy way to do with this the controller alone. If what you have can effectively be handled with RollingUpdate configuration alone, that probably suffices without further configuration: the controller will update targets (with equal weight) as new service endpoints come online.
If you need more complex logic, while there’s nothing in the controller that handles this (I may be wrong; @hbagdi do you know of anything?), the Kuma Traffic Route policy is intended for canary release handling and is compatible with the controller. Would that work for you?
Can you provide any documentation on this NGINX ingress feature? I wasn’t able to find anything official on it, and am not sure I fully understand how it functions.