If you had a MiniDV or Digital8 camcorder, and wanted to import digital video with minimum loss of quality, it might be worth jumping through hoops to try to find all of the equipment you need (some now discontinued, and hard to find) to make a FireWire connection.
For an optical drive? It isn't worth it. Apple never made an adapter to go straight from Thunderbolt 3 to FireWire, and by the time you finished stringing together a $50 Apple Thunderbolt 3-to-2 adapter with a now-discontinued Apple Thunderbolt to FireWire adapter, you'd have spent about as much as a new optical drive costs!
Just buy a new optical drive, like one of these:
24X OWC Mercury Pro USB 3.2 (5Gb/s) Super-Multi DVD/CD Burner/Reader External Optical Drive with M-DISC Support
That one comes with a short USB 3.0 B to USB-A cable. If your iMac is one of the 24" Apple Silicon ones that only has USB-C ports, there are several ways to overcome that, including
Note that USB 3.0 B is a "double-decker" connector that is taller than the single-decker USB B ones that you find on many printers. So if you go for a replacement cable, be sure to look for the "3.0" in the name.