just noticed if discover dead wastelander / scavenger etc and drag body to safe location with out searching them will eventually respawn alive but most will tell you to mind your own business if talk to them
even after 200 hours of gameplay i still havent found the sniper shack or the mole rat racetrack
if you complete blood ties quest in arafu one of the people will add "rock breakers last gas" to your pip boy map
at rock breakers last gas run to the nukacola machine and look at the horizon on the left side the sniper shack (wooden building) is wright at the top point
couple places i found unmarked not recently but on second play through is
the dog settlement just south side of the road at reclining resort homes wander if fa3 dogmeat originated from here ?
an unmarked ant nest just north from paradise falls
discovering feril ghoul settlement with burnmaster unique flamer for first time ,the drainage entrance is along the water front north from wihelms wharf at the time first play though i did not have enough skill in pick lock to realize it connects to falls church area and has 8+ of almost every schematic item needed
also south from red racer factory you can swim through the flooded section at flooded metro to another closed off area initially i thought it would connect to wihelms wharf drainage but it doesnt