In Russia’s case, I’m pretty sure it’s a bunch of republics within the country that technically govern each other but aren’t sovereign, I can see where that came from since the USSR was literally just a bunch of self governing republics uniting under the common goal of socialism (it’s in the name). Hence why Russia calls itself today the Russian Federation.
As for Germany, well… Federated Republic of Germany. I’d assume its regions are very similarly self governing, they just don’t call themselves republics here.
There’s the Swiss Confederation. Not sure what the “con-” prefix means.