Can anyone recommend an external disc READER so that I can access archived photos from cds to my iMac M1?

I don't think there are very many optical drives that are read-only these days. Once the ones that could both read and burn discs became cheap enough, there wasn't much of a demand for the read-only ones.

Note that an optical drive itself will not show up in the Finder. Only discs with something on them, or placeholders for blank discs that you are going to burn using the Finder, will. (The Desktop icons and Sidebar entries represent volumes, and in the case of optical discs, the volumes are associated with the discs rather than with the drive.)

Also, if you want discs to show up on the Desktop or in Finder sidebars, you need to go into Finder > Settings…, and tick off the checkboxes for CDs and DVDs in the General and Sidebar tabs.

Note that with bus-powered drives, you may sometimes run into power-related issues, e.g.,

• The drive may want to connect to two USB ports on a computer, so that it can grab more power than standards call for a single USB 2 or USB 3 port to provide, or
• The drive may be very picky about where it is plugged in (the Apple USB SuperDrive is a bit infamous for this; it has a reputation for not working when plugged into third-party docks and hubs).