I'll probably add this as a sub-mod, but I want to add two new technologies, High Pressure Infrastructure, and Vertical Terrestrial Architecture. All worlds will then get a blocker that reduces maximum districts based on terrestrial land cover percentage, that would be able to be removed by Vertical Terrestrial Architecture. Most species would begin with this technology. Planets would also get a blocker that reduced maximum districts based on ocean land cover percentage. This would be able to be removed by High Pressure Infrastructure technology. When a new world is colonized, the appropriate blocker will be removed during the establishment process based on which techs your empire has researched. When you complete research of the tech, any existing blockers on you're empire's planets will automatically be removed. When you conquer a new planet (not just occupy it), then the blockers will be created/removed based on your techs. As such, if you take over an ocean world with underwater infrastructure in place, you won't be able to build any new districts until you have researched High Pressure Infrastructure, but the existing districts will not be destroyed.

I will then add two civics.

1. Aquatic Start with High Pressure Infrastructure instead of Vertical Terrestrial Architecture. They will also get the Aquatic racial trait, which gives them +20% habitability on world-wide ocean planets, and -100% habitability on planets with without any oceans or large seas. Their buildings and districts will be flagged as aquatic, so only Aquatic or Amphibious species could work them. A new technology, Aquatic Breathing Apparatus would allow them to work in open air jobs and grant them regular habitability on "dry" planets, while the new technology Underwater Breathing Apparatus would be required for regular species to work aquatic jobs.
   
2. Amphibious Starts with both High Pressure Infrastructure and Vertical Terrestrial Architecture, and gets the species trait Amphibious. Able to work and build either open-air or aquatic buildings. +10% growth on Wet and Inundated worlds , but -20% growth on Dry planets.

The other thing I'll be working on next is to make more specialized planetary deposits, so then when you terraform, the deposits will change out and nudge the districts available depending on your terraforms. I'll add in a notice if any current districts would be destroyed because of this.

I'm not sure if it should be here, or in regular comments section, but heck.
I guess that some habitability perks should be fixed (or at least Crag world preference).
Species with Crag world preference have higher habitability on Mangrove worlds than Glacial worlds, and as far as I understand the mod, it should be vice versa.