I admittedly never finished Tunic, but that does not seem to fit the refined metroidbrania criteria? While there are shortcuts that can be had with fore-knowledge, the game has quite a bit of traditional metroidvania in that you need utility item X to advance past y. While there are rules and systems to be discovered from the manual, the game is still a version of get the dynamite, to unlock the boomerang, to get the wand, to unlock the final door.

Outer Wilds is a much stronger fit for the category where the entire world is accessible from the start.

Aside,

The Sorcery! series is massively underappreciated. It is an incredible trilogy and a loving recreation of the height of 1980s game books.

Highly recommended. I am sad the developers didn't make the fortune they deserved off of the series, purely because I want them to make a lot more games just like it.