Name your favorite game ready asset that "just works" upon import every time

I've been thinking a lot about how best to architect assets which I am working on.

Things like following SOLID in code, writing unit tests for code, Unity PlayMode tests, organizing my code, media, and meta data into logical folders and sub folders, separating code from data with SOs, and writing good documentation seems like a good start -- but what I really want to do is this:

I want to release assets that when imported it into whatever (supported) version of Unity, the developer can drop a prefab into their existing project and it just works (or intuitively guides the setup) every time.
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My assumptions here are that my assets will need to deal with (or to use a wizard or inspector to walk the developer through merging with):

• both input systems
• all three rendering pipelines
• fmod or native sound with mixer channels
• camera setup (controls + layering)
• compile target limitations (I'm looking at you Mobile and WebGL/webASM)
• and probably a dozen other things I'm not thinking of in this moment

So with that goal in mind, I'd love to hear from the community about game ready assets (such as a player controller or a UI system) that just works for you every time no matter the current version of Unity, camera setup, rendering pipeline, etc.

There will be extra cool points awarded if you can name multiple assets that "just work" together (e.g. a tree generation tool that also just works with a weather system which also just works with the time of day system, etc).

And lastly -- if anyone knows of any good writeups from other asset developers on this, I'm hungry for knowledge on the topic.