Got deploying to work using this article. Just some notes for whoever attempts the same thing:
If your account was created before 25 February 2021 you can't use s01.oss.sonatype.org and will have to use oss.sonatype.org.
The uploaded artifact needs some time to be validated, so the release may fail if you try it immediately. You need to implement a retry with delay to make it work.
Publish a Java library to Maven Central without Maven or Gradle
https://mccue.dev/pages/6-1-22-upload-to-maven-central