This is everything ive worked out so far, hope this is of help to some people, will be further providing updates as i figure out more. Each letter and number follows the zelda map grid
H7 cave - trophy room
H8 cave - spawn
J4- healers cave
L1 hidden cave - Behind cardboard cutout house notch cut into rockface, leads into a hidden cave.
M1 cave - locked coffin in an empty cave
M8 cave - woman in red dress gives you lucky numbers, unsure if these differ between players
N1 cave - Dialouge with a dude, says "legendary weapons for legendary enemies"
N3 cave - an animal dude called doctor cuarga, says "drink one of my blood bags and be more vital than ever
N8 cave - a cave with a locked coffin? Nothing else in the cave
O1 cave - water pool with warning signs about drinking from it, can make you gain or lose stats if you do, may have to repeat a few times for a result
O2 cave - Water vortex that spits you out at O4
O6 cave - You can gain the boomstick from this dungeon cave, enables longer travel as you are less likely to lose health traveling with the boomstick
P1 - does not seem to be there as it is on the map
P2 - a letter for mev at the base of the biggest tree
P4 - yacht location
P7 cave - no access to this cave, supposed meeting happening inside?