Talk to your airline's customer service desk but...
Most modern phones charge with a standard USB lead and many hotels and cafes (and even trains and buses!) have USB sockets these days. There's sure to be an electronics shop at the airport where you can buy a lead and, if necessary, an adaptor from the local mains wall sockets to USB. As I recall, Frankfurt has a huge shopping centre even before security.
Likewise, airports almost always have pharmacies where you can buy a toothbrush and toothpaste. OK, you already own those things but it's hardly a big deal wot have two tubes of toothpaste on the go at once, and your toothbrush will need replacing in a few months anyway. So you're just buying replacements early. Admittedly, you're paying inflated airport prices but that turns "a few" Euro into "several" Euro at most.
I always put things like phone chargers in my carry-on. You might want to do the same with toiletries but I prefer to put them in checked luggage to avoid the faff at security.