Flix seems to be implemented in Scala 2.13. Should we expect Flix to work anywhere Scala 2.13 works? ie: if Scala 2.13 supports JDK 8, should we expect that Flix will not take advantage of later JVM features?
The implementation language does not affect the target "machine". Also Flix is implemented in both Scala and Flix (but GitHub does not yet recognize Flix code). Flix targets Java 11, but is moving to target Java 21, and will take advantage of all features available there, including Project Loom. We are just waiting for Java 21 to become a bit more widespread.
(I am one of the developers of Flix).