itch.io

Soulblighter Music is right, Stoat is good, although still somewhat rough in some regards in my opinion, it's still open source so it runs on community contributions and donations.

Some other good ones that are worth giving a try:

• Root: https://www.rootapp.com/
• Fluxer: https://fluxer.app/

An interesting but harder to set up alternative is SpaceBarChat: https://github.com/spacebarchat/spacebarchat

It's basically self-hosted Discord, so instead of having Discord host your servers on their infrastructure, you host them on your own machine and use the Discord client API interface to communicate with the server. This means using it exactly like Discord, with the bonus that there's no one to monitor your activity there since you're hosting the server on your own private machine. Self hosting also means you bypass age verification, telemetry and all of the privacy critical concerns.

It really depends on the engine you're using or the way you're making the game. In my experience, the biggest trove of assets with very high quality  (4K) can be usually found in Fab for Unreal Engine. For example looking for ships:

Looking around I found an imitation of a Napoleonic ship and exports in Blender format to be used in other engines (it's also free :D):

If you don't want to be locked to mostly Unreal Engine, you can try cgtrader:

For example this one looks pretty cool:

I don't know how old you want the ships to be and how you're making the game but I'm sure you can find something there. If nothing satisfies you, and if you're willing to pay, you can always hire a 3D Modeler and give them the reference pictures to what you want them to create. However, that can get quite expensive, and if you're not sure of what you want you may even need an artist to draw concepts to bring your ideas to life. I'll leave the links to both Fab and cgtrader so that you can go look around. Good luck!

Fab: https://www.fab.com/search?listing_types=3d-model&q=ship

Cgtrader: https://www.cgtrader.com/3d-models/ship