Yup, i gonna give it 10/10 coz its more interesting n funny than the anime version. Actually, i cant' stop laugh when watching this HAHAHA. The story a little bit different than the Anime version. It's different but it's actually good (not every live action gonna be success to entertain their viewers). I don't know if this get into "SPOILERS" review category but i think i was already spoil it with my "The story a little bit different than the Anime version" sentences. I think that's important to otaku coz they're busy to watch their anime (watchlist?). Back to topic, Grand Blue (2020) is recommended for someone who want to watch light story, funny, entertaining, kill stress when u stressed. U must think "Why is it naked? Why the guy naked? Why there a people watch this?" Yeah, for people who don't watch the anime version gonna get that. But, its funny n there is no gay scene so it's safe.
Idk about the manga version. I dont read it. I just watch the anime. So don't blame me if it different from your expectation

I think it can be rewatched many times. Every you stressed, deppressed just rewatch it again. It's gonna kill them