It’s not quite as simple as that, is it? What if they ask for a utility bill under your name with less than 3 months? You’re screwed. Online brokers are the same. If you cannot prove residency, forget it.
@sgupton , FYI and I’m not sure if you realize. N26 has been prohibiting non-residential address to send card. I know this because my N26 Standard (Mastercard Debit) is due for renewal this year and I’ve tried setting my address to my Clevver address in Germany and it was rejected (i.e. they know it’s not a residential address). I haven’t tried any other (virtual mailbox) addresses as I only have one in Germany - I still have to find a way to receive this card! 
(Anyone has an address in Germany I can use? I’ll pay for your shipping!)
So buyer beware, if you plan to sign contract with Clevver (or any other virtual mailboxes out there) as N26 may not be able to send your card. If your experience is otherwise, please post here.
Thx!
Disclaimer: Yes I know N26 Standard these days does NOT come with free Debit Mastercard (it cost 10 euros per card) but I was grandfathered in (having an account with them prior to 2020). N26 Standard nowadays come with only virtual Debit Mastercard (but I still like the physical plastic, just in case).