Are developers not need packages such as SDKbox? Why such packages aren't in priority?

I want to create mobile games in Cocos Creator, but the lack of packages for native functionality don’t allow me to do. I know that maybe it is just my problem and I can write my own packages, but It can take a lot of time, to understand principle and then write scripts of Android and IOS in languages I never used.
For my just interesting, if developers aren’t require all this stuff?
IAP, advertising, leaderboards, Local Notifications, access to camera etc…

Maybe we can find a developer who will create such package and pay him, or he can create paid version in Cocos Store.

Maybe the developer is using a package that replaces sdkbox,like:
https://service.cocos.com/document/en/sdkhub.html

I prefer to write my own as it becomes very easy to upgrade libs whenever required.

Would you share some example project ow your own native functionality?

Currently I cant share publicly but its very simple.
3 things you need to work on

  1. How to call TS to Android Java
    How to Call Java methods using JavaScript on Android · Cocos Creator
  2. How to call Android Java to TS
  3. Implement plugin directly into Android from official website (Admob, IAP, etc)

For the first time it might take sometime to develop but after that you can use it in every project, Also upgrading will be easy

I tried to do, but I don’t know where to put all this code in project. For example, I tried to create android notifications:
Created static class Notification.java and run method in the AppActivity.java

and I am getting this error on make:
[Build] make package D:\my_work\cocos\Idle Game Prototype 3D\build\android failed!

@linrm that Cocos Service is free?? or you charged for it.

Cocos Service is free for developers to quickly integrate services through the Service panel for the game.

Service is good, but there is lack of possibilities… SDKHub just for Huawei (no Android and IOS)
No notifications implementation and etc…