We have been using Kotlin for Spring Boot and Ktor microservices in AWS for the past 3 years.
My C# .NET team was told all new development at the company had to be on the JVM.
I couldn't abide switching from C# "down" to Java, and realized Kotlin would be a more natural change for the rest of the C# devs as well.
It is now a "standard" development option for our company, and at least half a dozen teams (other than mobile) have opted for it.