I have found many free resources for learning Japanese. There is a YouTube channel called Japanese Ammo with Misa. Misa sensei explains different grammar topics and give a lot of examples. I really like her channel.
For practice with reading hiragana and katakana, I recommend writing words/sentences. I would watch Japanese Ammo videos or Cure Dolly videos (another YouTube channel that teaches Japanese grammar) and I would write down the examples sentences and the grammar points. Eventually I improved my ability to recognize the kana, as well as write them from memory.
If you have Disney+ or Netflix, you can change the language so that the movies and TV shows will be dubbed. Disney+ has this feature built in, so if you start any Walt Disney Animation Studios or more recent Disney movie or show, it will have many language options available. Pixar, Nat Geo, Marvel, and Star Wars don't seem to have this feature yet on most of their content. In Netflix, you can add languages in Settings and it may give you the option to switch languages for certain movies and shows. I think it's great practice and fun because you can watch what you want while listening to your target language.
Podcasts are great for listening practice as well. There are many free podcast series. Nihongo con Teppei is great for beginners. I like Learn Japanese with Noriko. Both of these can be found on YouTube or others podcast apps. I'm not familiar with any German podcast series but you could search for something on YouTube.
italki is great for practicing speaking and for finding teachers. It is not free but it can be very affordable. Many teachers offer 60 minute lessons for $10-15 dollars. There is also no commitment to stick with the same teacher. You can choose to schedule one lesson with a teacher and never schedule any more lessons with that teacher. There are so many teachers to choose from so you are sure to find one that will fit your needs.