for una
u must interact with her for 5 days (in real life)
after completing all ghost quests then talk to boatman for achievement and a chest

You have to finish all the ghost quest before talking to the boatman then poof done

You get an achievement after completing it all too.

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If the boatman keeps describing one of the ghosts, means you haven't finished that ghost's questline. If everyone's is done, talking to the boatman will initiate a convo and a short cutscene before you get a precious chest.

Una finally finished, but the boatman still staying the same line, is he suppose to give rewards after all the ghosts completed?

I finally finished it, Una and Abe were timegated. The boatman started saying the same default message but when talking to him a second time he finished collecting everyone. Good Luck!

finished una already, still the boatman keeps saying same thing, like its still waiting for someone else to sail the boat?

As you guessed, Una quest was 4 day c****s. I've finished it, now the last one I needed to was getting the charm from fishing spot. I've failed twice and also the spot will regen each 2 days, making it quite a h***le. :(

i did them all but for some reason its not working..the boatman isnt doing anything different
somone pls any advice?

talk to Una 2x every day and after awhile itll have an option to give the sachel for her request

I went back to the field of mushroom where Abe scold us and he talks about the boat, Una and mushrooms from outside the island. I gave him 2 types of mushrooms and get the treasure chest.

Beautiful guide! =D

Here is detailed video guide if someone needs it: https://www.youtube.com/watch?v=tqO8EsvukxA