Visas are almost everywhere, and supermarkets and shopping malls must have them; Buying train tickets and air tickets is definitely no problem if it is on-site credit card; German railway online booking basically only accepts credit card payment, but it has to pay a certain formalities fee; Online booking is also available on airline websites, with different regulations.

If you study in Germany at your own expense, you must open an account with Deutsche Bank, and you will get an EC card, which is equivalent to the domestic UnionPay debit card, and it is also very convenient to use.