In 2021, Germany got 55% of its gas from Russia (the rest from other European countries). Depending on how much overall consumption can be reduced, European suppliers might be able to cover most/all of it.
European suppliers will also be busy covering all the other increased demand inside from Europe [0], the demand that most people tend to forget when they act like Germany is the only country dependent on Russian energy, and resources, imports.
It's also not as easily replacable as "Just go to the other gas supermarket down the street", infrastructure needs to exist and support such supply chains.
"Habeck said imports of Russian oil now accounted for 25% of German imports, down from 35% before the invasion, and gas imports have been cut to 40% from 55%. Russian hard coal imports were down to 25% from 50% before the invasion."
It's also not as easily replacable as "Just go to the other gas supermarket down the street", infrastructure needs to exist and support such supply chains.
[0] https://www.statista.com/statistics/1201743/russian-gas-depe...