Edeka has all of them.
Lastschrift is SEPA Direct Debit, so if you have a residency in Germany + EU IBan I'm pretty sure it should work (Worked with Revolut LT iban atleast for me)
Handytarife günstig sichern: Alle o2 Smartphone-Tarife just make sure to check the option "Ohne Laufzeit" which...