How about bureaucracy processes and getting up and running with internet, gas, bank, etc? Doubt that call centers have English speaking guys or forms in other languages
Many internet, phone and other companies employ young people for support tasks who can speak english most of the time, so it shouldn't be a big issue. Especially if you go to offline stores in Berlin to fill out the forms.
Don’t bother trying it before you actually move though, because the website appears to be geo-locked and the American and UK versions aren’t open yet.
> an online-only bank
It's a direct bank as any other, quick internet search will reveal more options in Germany. Their "innovations" in comparison with personal banking even in neighbouring Czechia (e.g. Fio), or Poland (e.g. mBank, Inteligo) are laughable.
I had originally tried getting an account in a Sparkasse branch, but it was much more difficult than N26. No doubt there are other online only banks, but I cannot comment on their quality without using them.