init script won't work if you meant export PYTHONPATH env setting. Databricks shell overwrites it when it starts the python interpreter. One approach we make it work is if the code is under /dbfs, we do editable install at init script, e.g.

pip install -e /dbfs/some_repos_code

this creates a easy-install.pth under /databricks/python3 site-packages at cluster initialization, which will append to sys.path to driver and worker.

This approach avoids appending sys.path everywhere in the code, which breaks the code integrity; easier to enforce at cluster level.

We also tried to do the same editable install for Repos under /Workspace but failed. Apparently /Workspace partition is not mounted during cluster initialization. We are going to request databricks to look into this.