My country has a really well developed Craigslist like alternative called ‘sahibinden’, essentially just visit the person you’re buying from or have a decently safe cargo sent over

I am thinking of making a new gaming PC, my old one basically has no upgradable parts, a GTX 1660 (No rtx), a dead-end low grade motherboard, and a 6 core CPU

How should I sell them? As a whole and just put the PC in together? As parts? How would I know to trust or to not trust the buyer? is there any use left that is better than selling it?