When migrating from Voyager to Alma, physical inventory item records without barcodes are absolutely permitted (in fact in some cases like special collections, archives, and rare books it is the norm to not have barcodes). However, some physical inventory items without barcodes may be excluded from various workflows in Alma after you migrate, and this might not be desirable.
This very simple query, which you can run using Voyager's Prepackaged Access Reports, will identify those items in Voyager without barcodes.
Note that there is a mechanism in Alma to add "generic" barcodes to such items, post-migration.
FROM ITEM LEFT JOIN ITEM_BARCODE ON ITEM.ITEM_ID = ITEM_BARCODE.ITEM_ID
WHERE (((ITEM_BARCODE.ITEM_ID) Is Null))
ORDER BY ITEM.ITEM_ID;
For other queries that may be useful, see my "Surviving Almanado: tips for a successful pre-implementation" presentation's Accompanying Materials.
If you need assistance in running custom SQL queries in Prepackaged Access Reports, consult the Voyager Customer Listserv.