Does he want to get into software? Or just into tech in general. Because a couple decades of supermarket managerial experience means he could offer a wealth of insights into point-of-sale systems tech - he has been using it for years already. Don't dismiss that experience - Use it.

He could go a couple ways, either looking for an entry level position settings up POS systems, and working up from there, or could try to get into product design with insights into was has or has not worked for his teams over the years. I'd recommend getting in touch with the vendors he likely already has worked with and inquire what openings are available.