This creates code39 barcodes using Unicode block characters. It doesn't always work on github since the font is exactly right, but you can see it in action at https://trmm.net/Barcode
This may scan for you if it is on a single line:
│ │█ █│█ █│ ││█│█│ │││█ │█ █│█ ││█ █ ││││█ │█││ │█ █│