Currently we describe setting up SSHFS for dev images to access working copies of repos in the README:
https://gerrit.wikimedia.org/r/plugins/gitiles/releng/local-charts/#sshfs-file-sharing
This should really Just Work, or at least be a one-command thing.
WIP: https://gerrit.wikimedia.org/r/c/releng/local-charts/+/497013