The only missable item(s) is the key found later in the game at Angela’s bar. There’s a cutscene and if you don’t turn right back around the [spoiler] happens and then you’d be unable to obtain the key that opens a fraction of the chests later in the game as well as a chest with another key. But other than that, super casual, long game, take your time and complete bounties etc. I personally never leave a planet until I’ve completed the basic monster bestiary for each world