In 2009, Gazprom proposed various alternatives to the main route, some including alternative routes through Ukraine that Ukraine rejected. In the end they shipped some ~12% of their usual through-Ukraine amount as additional shipments on other routes. Doesn't sound like russia was unwilling to deliver. But I'll concede that point as uncertain, given that the EU fact finding mission to figure out who stopped the shipments to the EU didn't come to conclusive results. (some data in https://www.cep.eu/Analysen_KOM/KOM_2009_363_Sicherheit_der_...)
In the end, I think Germany should have gotten out of fossils in general, no matter what happens to Eastern Europe once the mafia-run petrol station that cosplays as a country feels the pressure. would've-should've-could've.
2014: "Asked if sanctions could affect Russian gas transit, Yatsenyuk said the move could possibly mean halting 'all types of transit, from air flights to transit of resources.'" (https://webarchive.archive.unhcr.org/20230603044044/https://...)
In the end, I think Germany should have gotten out of fossils in general, no matter what happens to Eastern Europe once the mafia-run petrol station that cosplays as a country feels the pressure. would've-should've-could've.