nearly ALL legacy printers and MOST older scanners work on Linux. At least as far as a basic scan to image goes.
Scanner support is actually one of the worst aspects of Linux these days. But its the newer ones that dont work..it takes time to reverse engineer them and come up with drivers. A few latest greatest printrers too are somewhat unsupported, though I have usually found something 'close enough' that to all intents and purposes works.
With printers since OS-X uses the same underlying print system, the PPDs 'printer description files - are generally available on Linux now as well. You can steal them off the 'installation' DVD'
scanners need to be checked thoroughly
There is some ability to get 'close enough' but some simply wont work at all, and others may in fact burn out if driven past the endstops etc.
If there is one piece of crud left in Linux, its SANE.