Under C7 I used to have a handy bit of code that used my webcam to read barcodes and QR codes. It just generated the strings, I don’t think it passed them to Firefox, but I’m happy with that. I’ve looked at zbar, but it is version 0.10 and appears to have been unmaintained for over 10 years. I did have a go at running ./configure but after multiple complaints of missing packages that were there I’ve given up with it.
The previous way was a couple of one-line scripts jacketing zbar. That’s why I went looking for it, but only found the old version mentioned above. I’ve added the repository and installed the later version you pointed me at (cavets accepted), and it seems fine. Thanks.