Title says it all. The Godot SDK for analytics at least (haven't checked the other SDKs) requires recompiling the engine to create custom export templates. Considering that all the SDK is doing is interacting with an HTTPS API, I fail to see why this SDK couldn't be implemented as a Godot addon and put on the Godot asset store like every other extension.
I understand that there may be some functionality that might not be available with this approach but when the entry point to using your service requires me to install a bunch of tools to compile a custom version of my engine and your competitors will just let me install an asset from the asset store within the game engine itself, I'm just not going to bother.