Who else here needs to do have shopify to add 2 accepted barcodes for one variant , the reason is we do fba , and print fnsku on products and now want to sell products using shopify retail pos , but in shopify you can only put numeric barcodes as thats all google accepts or its gmc wont accept your products . So if we want to use pos we will have to relabel our products with the barcodes that
The only thing that comes to mind that might help you is to use metafields.
Metafields can contain extra information on a product or variant that you're not able to add in the Shopify Admin. You can then name a metafield "fba-barcode" (or whatever you like) and "fnsku-barcode". You can find several apps in the app store that allow you to edit these metafields.
Using these metafields and passing the correct data to whatever service it needs will be the tricky part. I don't know where you want these barcodes to show up or where you need to sends them to, but I think this will require some custom work as well.