Buy it. Larian is a small studio that put a lot of effort and love into that game. If you like what they do, support them. You can get it DRM free on GOG, so you get to actually own it.
It's not about being helpful in the sense of just answering the question at hand. If OP just wanted the question answered they can just Google it. Instead I wanted to offer an alternative, low risk solution.
While Ubisoft, EA and consorts can easily stomach some piracy and still crank out "AAA" titles in a 6-months interval, it hurts small studios relatively more. Buying and returning, on the other hand, offers a way to give feedback to the studio via the return reason and costs just as little as piracy.
ProtonDB says it's decent, the game is Steamdeck verified plus you can return it with under two hours playtime, so I'd just buy it.
Any upgrade path with a pirated version should be completely irrelevant.
First of all, I can evaluate whether I like the game or not, see if it runs well enough for me. I know Steam has a 2 hour window for a refund, but that it less convenient than testing the. Game in other ways.