Can you get Spotify & Netflix as a trainee cheaper or are there good cheap alternatives?
As an apprentice, this will be difficult, if not impossible. But there are such offers for students and students, look at times on such sites, if necessary there's also something about education.
https://studententarife.de and similar pages.
As a student you get Amazon Prime for ridiculous prices. If you are at least 18, you can try it as a student. https://www.schueler-forum.com/thread/2469-geld-sparen-mit-sch%C3%BCler-rabatt/
But first you need a student ID from your vocational school.
There are some free streaming services, maybe interesting for you too:
https://www.smart-wohnen.de/entertainment/artikel/wow-die-besten-kostenlosen-streaming-dienste/