What is the best way to use maven builds in gradle composite builds? I know i can just run the maven build and install to a local repo and then use that but is there a better solution?

You could maybe knit a Gradle wrapping-build around it that runs the Maven build and provides the built artifacts like it would have built them itself or something like that. But whether that is "better"? 🤷‍♂️ There is probably little evidence about "best" way as it is not a to often needed use-case.

my usecase is big OS projects that use maven like quarkus, and i want to work with github main branch.

The easiest I know is indeed the intended way of the target system, so do

mvn(w) install

and use it from

mavenLocal()

, but with a repository content filter and as last repositories entry.

makes sense!