The main concept here is finding those special relic locations on planets marked as ruined or abandoned, and i've got some solid info about that. You'll want to scan for specific descriptors in the planet bios, and once you spot those keywords you're probably in the right place. Those polished stones you mentioned are definitely real and super useful for both building and charging, while the memory stones youll find scattered around will unlock some really neat exotic building pieces

A heads up though, that eissentam (it's actually the 10th one) is definitely real but you'll need to work through some story stuff first to reach it. That ukl galaxy mention isn't quite right though from what we know. Something interesting that wasn't covered - there's actually some expedition-specific stuff like digging up ancient bones and taking on guardians that ties into all this

The basic approach of targeting abandoned planets still works great but make sure you're stocking up on chromatic metal and ferrite dust for warping around. Those ruins you find will usually have memory stones nearby and they're your ticket to getting those special blueprint pieces that show up in the exotic section of your build menu once you unlock them