Missable achievements? Xbox

Hello everynyan, I just beat the game today and am now in the process of exploring all the new areas unlocked in act 3. Was looking at the achievements and saw cosmetics and songs were an achievement and some where supposedly missable. Specifically the first Gestral trader you encounter doesn’t come back again?(i forsure didnt buyout his shop so woops) And a Maelle disc.

How true is this? The info i scoured is like release time old and i know the devs have made other missable things reobtainable so would like up to date knows. Push comes to shove after i finish everything i can go into ng+ which i plan to do anyways. Still would like to get everything in the first go around though.

help please and thank u🙏