This gist describes the process we've used to migrate our Maven package repository from Sonatype Nexus to GitHub Packages. The same process could be used for migrating any Maven package repo that is in the standard layout.
We created a special repository on GitHub to hold all of our Maven packages. You might decide to migrate packages to different repositories, in which case invoke the script multiple times.
The script uses find to look for all of the folders containing poms and upload them. You specify the folder