Can anyone recommend a good laptop or iPad for up to 350 euro that can be used well for school?
Take a look around https://www.hardwaredealz.com/die-besten-gaming-laptops-und-notebooks here
If you want to take notes in class, use an Ipad. Their pens / software are the best.
If you write on paper anyway and only need the PC as a hub for online lessons, take a Linux computer or an old Win and install Linux. It's more complicated, but you get used to it and Linux runs fine even on old laptops. If you are looking for value for money, you can't beat self-built tower PCs. Take a look at classifieds for used PC with at least 8GB DDR4 RAM and 4-core processor. Plus a cheap monitor and normal headphones as a headset.
buy used but make sure that everything works and do not pay PayPal to friends or bank transfer, because you can't have the money withdrawn
Which iPad up to 350 euro would you recommend?
You can't get a new iPad with a pen for 350 euro, you might be lucky on eBay. Otherwise the Tab S6 Lite would be on the market for (RRP, meanwhile cheaper) 379 euro. There's also a pen for writing. The tablet is completely sufficient for simple note-taking at school / during video conferences and for video conferences.