Do solids settle out of air on a high gravity environment faster? The air would be thicker. Does gravity or buoyancy win than tug of war?
I spent a day once trying to figure out what the Bronze Age would be like for marine creatures. Oxidation is less of a problem but galvanic action is huge. Fire pretty much doesn't work, which blocks a whole bunch of precursors like ceramics.
Atmospheric density it a little more complicated: Venus has the same gravity as Earth but a thicker atmosphere, while Titan is a lot smaller and still has a surface pressure 50% more than we do at sea level.
The big problem with marine technology isn't that it's totally impossible, it's that there's vast gulfs between various achievements and little sign that continued progress on some matter will lead somewhere. You could raise jellyfish to be transparent and lens shaped and build some telescopes, but how do you figure out that's a thing that might be a good idea? You might be able to turn an ocean vent into a forge, but how do you figure out that's a good idea? We had a path where we noticed certain rocks in a fire ooze useful metal, for instance. We didn't deduce from first principles the Periodic Table, guess the properties of metals from logic and maybe our interactions with (very soft!) silver and gold, determine it was likely that some of those colorful rocks are metallic salts, and then determine they might be useful to mine. We found they were useful to mine, then after thousands of years of civilization built on top of the resulting tools, only then figured out the why of a lot of those things.
This is one of those places where it's really a good idea to understand that despite the pretty Just So stories where science pre-dates engineering, in reality, engineering extremely frequently has predated science, at times by centuries. How are water-bound creatures going to figure out enough engineering to even get science going?
Certainly, as I said, they can breed things, but how do they even know where to try to go? How do they maintain the discipline to breed things over hundreds or thousands of generations? How do they get to genetic engineering?
There may be answers to this question but they sure aren't obvious.
I spent a day once trying to figure out what the Bronze Age would be like for marine creatures. Oxidation is less of a problem but galvanic action is huge. Fire pretty much doesn't work, which blocks a whole bunch of precursors like ceramics.