Hi Simon:
You pose an interesting question. I will do my best to answer.
First, you mentioned older technologies. Helidon was introduced to the Java community in the summer of 2018. Similarly, Micronaut and Quarkus were introduced in early 2018 and early 2019, respectively. Relative to, say, Spring Framework (introduced circa 2004), I would think that these are newer technologies. But, I totally get what you mean.
I believe that I addressed this in Chapter 1 of the book. The section entitled "Helidon and the Java Community" describes instances where Helidon has been integrated with other technologies such as: GraalVM, Micronuat, the Jakarta Persistence specification, Kotlin, MicroStream (now EclipseStore). For GraalVM in particular, you were able to create native images of Helidon SE applications starting with version 1.0, but not Helidon MP applications due to the heavy use of reflection. However, one of the big features of Helidon 2.0 was that the Helidon team was able to overcome the reflection limitation such that Helidon MP applications were able to be converted to native image.
Also, Helidon is unique with its SE and MP flavors. The former is functional style and offers components such as: a web server based on virtual threads, a web client, security and observability (metrics, fault tolerance, etc.). The latter is declarative style with heavy use of annotations and is an implementation of the MicroProfile specifications. You can use any Jakarta EE-compliant application server to deploy your applications.
I hope this answered your question and something for me to keep in mind moving forward.
All the best,
Mike.