Since Subnautica 2 is so close now. Apart from the obvious stuff like larger deeper ocean, silent protagonist etc. What are your NEEDS for the game. Something that NEEDS to be in the game for you specifically?
Mine would be a better inventory. Items that stack . The current inventory is sometimes so cumbersome when you need to craft like 50 things at once that need multiple items. Maybe make it so that seeds, resources and food items stack upto 6 pieces in one slot. Obviously. you wouldn't be able to stack tools like scanners and vehicle bays. But just being able to stack multiple basic items like titanium would so so good.
This way you can have recipes take more items to craft because currently, crafting a whole seamoth with just 1 titanium ingot, 1 lead and like 2 glasses is really funny.
This also makes it so that you need less storage for more items. Having a billion lockers just to store like 60 titanium sucks. This is not an inventory management game but you spend the late half of the game looking more at the recipes and menus than the actual game.
Anyways. That was my rant. What are some of your needed features?