When using Add-PnPListItem with Batch specified and item having managed metadata / taxonomy field value specified (term name, not guid), there are still http requests made by PnP.Powershell to get GUID for term that is set in Add-PnPListItem Values
Ideal solution would be to get GUIDs for the terms specified by name in one BATCH before executing BATCH that actually adds items to the list.
This is mostly nice to have thing as I imagine this would be quite hard to implement.