Amper approach towards a declarative build tool, moving away from kotlin script (and gradle) is very sound.
A while ago there was a debate in the Scala community about sbt which describes a project in a subset of scala.
Using a well-know DSL to describe a project will offer better tooling support.
I hope that Amper will be a modern version of maven (minus the XML, and the plugins)
I think that Rust's cargo should be the benchmark for Amper.
Simple, fast, powerful.