Following up for others facing the same issue:
You need to run neo4j-admin import as the neo4j user (as this user is used on starting neo4j and it cannot obtain a lock on files it does not have access to/own?). Therefore I ran sudo -u neo4j neo4j-admin import ... and was able to import that other graph data and get the neo4j instance running sudo systemctl start neo4j.
Also make sure to remove any previous import.report files as the neo4j user may not have access to overwrite this file.