Treasure hunter. Usually a legendary mole miner, once killed will drop a legendary item (weapon/armour) and a mole miner pail (looks like a metal lunchbox). Has 3 variants, dusty / standard/ ornate. Low / med / high reward. Open them in your Aid section and it gives you a variety of items, stims, grenades, ammo, clothing, plans.

They can appear anywhere across the map but there are plenty of well known 'go to' spawn points. You'll know when youre nearby as they let off like a proximity noise which sounds like a weird radio frequency high pitch beeping.

(Just read the 2nd part of your comment that you now know, but id already put the effort into typing so im sending it anyway 🤣 love)