I'm on the brink of writing SuiteScript for this but really want it to be SuiteFlow if possible. Has anyone figured out a way to approve a transaction based off of fields at the line level? e.g. Purchase Order. If I have 3 lines each with a different department, I would like each department to approve the transaction.

saved searches are generally the way to incorporate unsupported line-level fields

Advanced Approvals might be able to do this.