my old one basically has no upgradable parts, a GTX 1660 (No rtx), a dead-end low grade motherboard, and a 6 core CPU
I still use a GTX 970 in my desktop, my laptop as a 4 core and I consider it beefy for my needs. There is always value in older hardware. It all depends on one's needs. Heck, last week I sold an old 90s IBM keyboard to someone that needed exactly that model. Sure it's an awkward keyboard (no Windows key but with an integrated trackpoint and trackpad) but it still works flawlessly and the guy was more than happy to buy it from me ;)
To answer your question, I would suggest to list all items separately, and here in France I would list them on a site like leboncoin (they offer decent buyer/seller protection and easy to use shipping as well as the ability to meet in person with, here again, nicely thought out payment system that reduce the risk of being scammed)