How can I send data from one smartphone to another?

From the Huawei Mate 10 Lite to the Samsung A9, all the contacts, what's app, messages, audio, video, photos… So everything is on the new smartphone

Google backup (google drive) is always available. In addition, you need a "contact backup" app which secures the contacts

the individual apps you can't transfer 1 to 1 which you will probably have to re-download or create apk files and send them.

Look here:

Have just written a comment. Is only about the detour with a laptop / PC in between. This is not possible directly.

And the app Smart Switch? I also heard something good

To access the data of the apps, you need root. However, you do not need root if you are in recovery mode.

Is something difficult grade at different manufacturers: /