To get to the point, Germany has a highly developed rescue system in place, so establishing yet another one makes little sense. Believe it or not, animal protection laws here are far more advanced than those in the U.S.. (I'm an American who has lived in Germany since 1982, so I have experience in both countries). Just to give a few examples, all shelters are no-kill ones, declawing, cropping ears and docking tails are illegal, there are many restrictions in place forbidding the breeding of "mutants", and vets may not euthanize an animal at the owner's convenience. Pet stores are not permitted to sell puppies or kittens, which helps to cut down on puppy and kitten mills.
You'd probably be able to contribute more by volunteering at a local shelter/rescue, than by starting your own, in Germany. The Czech Republic may very well be different, but please don't go there thinking that U.S. laws are better, and you're going to "teach them the right way". The EU has far more stringent animal protection laws than either the U.S. or Canada, and northern or western European countries' laws will be an eye-opener for you. The southern and central/eastern countries are lagging behind, due to their relatively new membership, but research before trying to "reform" the system.