All purple or blue unique items will be worth 0 gold and therefore stay in your inventory when you change maps to the next chapter.

Copy items.ini into your game directory:
\Legends of Eisenwald\Config
Backup and then replace the original items.ini
Do the zone change
Restore the original items.ini or not

Play the game...

https://drive.google.com/file/d/125zL6X27FcKkw1S1-E1cAHFUwJLn5019/view?usp=sharing

https://www.youtube.com/watch?v=8mnJ0r-rkrY