Unity package. Fully cross-platform async library for strict-OOP.
In contrast to traditional language-specific patterns, it does not rely on a static execution context.
Does not reference Unity Engine, so it could be used in a regular C# project.
Make sure you have standalone Git installed first.
In Unity, open "Window" -> "Package Manager".
Click the "+" sign on top left corner -> "Add package from git URL..."
Paste this: https://github.com/forcepusher/com.bananaparty.async.git#2.0.0
See minimum required Unity version in the package.json file.
All of these are not suitable for strict-OOP. They've copied the same mistake from each other.
C# TAP (async/await) SynchronizationContext
Java Future ExecutorService
JavaScript Promise EventLoop
Simula Process (Activate/Hold)
Relying on a static execution context is not okay no matter how you approach the thing in question.
I know it looks very convenient - but it's a trap. Those tools can only be used at a program entry point class.