ai – Long term commitment

I am new to game developing and anything related to it.
I do understand that recommendations about starting small projects before going to a big one is a thing but I want to jump right of my desired big fish, no matter how hard it can be.

So, I am set to do a isometric view-like 3D game that besides walking, collecting resources and interacting with creatures and some objects, the whole thing is about simulation. I mean, I want to create different creatures that have different behaviors and they live together in the same space. Almost a scripting various animals to eat, sleep and even walk around.
This game is supposed to be an audio-visual allegory. Almost like watching a aquarium or going to a national park to watch birds…

The art is will be low-poly, with an 99×25 pixel .PNG texture for all the possible colors of the game.
For performance and easing the process of creating various things since I am a one-person team.
I mean I really do care for performance, in Blender, when it is possible I use a triangulated branch rather than a cylinder or squared ones because the number of the faces the computer has to load…

So, I am still in doubt about creating it Linux exclusive (for promoting such a good concept of open-source stuff (I know that Linux exclusive can sound contradictory but well, some sacrifices sometimes are necessary)). However since I have a nVidia card, I still in doubt of adopting Windows.

AI dialogues in creatures sounds a thing. What is the path to research about it?

OK.. I want to work on this project for a long time, like Dwarf Fortress brothers or any other long-term project software.
A game engine is suitable for this kind of practice?
In my research I still have doubts about Godot or Unreal Engine. Both having major upgrades this year (4.0 Godot and UE5), I decided to take the time until the release of it to learn C++ on learncpp.com so when they release it I can start digging with a better confidence than a noob learning the basics without coding background.
Yet time to model objects and create music to have at least some already scenery made.

Any advice?

(time is not a problem and I do not care to take a year or two to grasp really well concepts to start messing with dev.)

Is a self engine too craziness and waste of time for such a beginner like me, considering the nature of my project?