At this moment we do not support accessing comments via the API. Here is a client app article with an overview of the shipment page that goes over messaging.

If Flexport is digitizing your commercial invoice, and this is itemized on your commercial invoice line item, you can find this in the items array of a container.
If you are looking at the shipment resource, for example, you add the parameter "?expand=containers" to your request and find your itemized data under data.ocean_shipment.containers.data.items
This is also available at the line item level in the commercial invoices object, under data.line_items.container_number.container_number

If Flexport is digitizing your commercial invoice data, product-level line data is available under the data.items array within a /shipment object.

You may query the /shipments endpoint using line-level parameters such as SKU (f.sku) or PO Number (f.purchase_order). It's important to also keep in mind that this data will only be available in a shipment after the commercial invoice digitization is complete. Exactly when that might occur in the shipment lifecycle is based on operations SOP (Standard Operating Procedure) for your account. Please reach out to your account executive for more insights into the SOP for your organization.

You can use the query parameters to find the list of shipments having a specific SKU (f.sku) and status (f.statuses.any).
If you were looking for shipments that were in transit, you would make a request with the parameter f.status.any = ["in_transit_to_arrival_port", "in_transit_to_final_destination", "in_transit_to_arrival_port"]. You can then find the ETA to the final destination by looking at the estimated_delivered_in_full date attribute for each shipment.

At this time there isn't a specific way to obtain a shipment by name, but you can use the f.metadata parameter to narrow down the list of shipments you get. If you know the shipment you're looking for has the metadata tag PO with a value of 12345, you can use the f.metadata.PO parameter to filter for only shipments with those metadata values.