Basically title says it all.

Action cam will be stuck on top of A1ii, main purpose is to film "everything" in the blue like hammers ect 20-ish meters away, scenery in Indonesia, ect.

Main is cost effectiveness, so camera and "original" housing from the camera maker.

Is wideangle wetlens needed? Or does the additional price justify it for my described use?

The price range and what ChatGPT is suggesting, are all the obvious suspects, GoPro 13 black, Insta360 Ace Pro 2 and DJI Osmo Action 5 Pro. And Inon UFL-G140 ZD.

The prices of this setup is pretty much what im willing to do splash out. Only thing is which one.

After using several GoPros for many years, I decided to switch to the Osmo Action 5 last year following extensive research, and I’ve never regretted it. Due to its smaller sensor, the GoPro has a significant drawback, especially in low-light conditions like those found underwater. Footage shot at greater depths and in caves/caverns/overhangs is heavily noisy, whereas the Osmo Action offers clear advantages in these situations.