I don't know really much of Swiss idioms, just a few (I live in Austria) so here is a short list of saying that I've heard from friends in Switzerland which are unknown in Austria, and so I guess they are unknown in Germany too:
- Ein sitzender Säger ist gleich viel wert wie ein liegender Scheißer.
(A seated sawyer is worth the same as a lying shitter)
Meaning: To do work right, you have to make an effort.
- Etwas für die Füchse machen; das ist für die Füchse
(To make something for the foxes; this is for the foxes)
Meaning: you make something, but it goes wrong, so nobody needs what you made
(In Austria we have a very similar saying, but with fish instead of fox: »Das war für die Fische«)
- Lobt der Trottel, so tut der Narr.
(If the idiot praises, then the fool does.)
Meaning: If you want to make a fool do something, you just need to praise/compliment him, which even an idiot can do.
That's all I know about Swiss sayings.
But I want to add something that is too long for a comment:
German is official language in many European countries: Germany, Austria, Switzerland, Liechtenstein, Italy (South Tyrol), Luxembourg and Belgium. And it is a minority language in many other countries like Namibia, Poland, Paraguay, Brazil, South Afrika, Russia and some others.
All in all there are about 100 million native speakers of German, and about 80 million of them live in Germany. Less than 9 million live in Austria, and the number of German native speakers in Switzerland is about 5 million. (Switzerland has 8.6 million residents, but many of them speak other languages.)
And this is the reason why all books printed in German language are printed in the standard variation of Germany. Books printed in standard Austrian German exist, but are very rare, and books in standard Swiss German are even rarer. (There are only standards for German, Austrian and Swiss German. Other countries use one of these 3 standards. A standard is a language that you use to write laws and other official documents, so the standards are not dialects.)
Even books written by Austrian authors, printed in Austria and produced mainly for the Austrian market are written in German German, because Austrian readers are already used to read German German, and if you write a book in German German you still can sell some copies in Germany, but German readers won't accept books written in Austrian or Swiss standard German because grammar and vocabulary are a little different.
And also all major German speaking private TV stations are located in Germany and they produce their program for people in Germany, but also people in Austria and Switzerland and other countries watch these stations. There are also official and private TV stations for Austria and for Switzerland, but they do not broadcast their program to other countries.
So, we have this situation:
People living in Germany are exposed only to one variation of German language. If they want to get in contact with Austrian or Swiss German, they need to travel to Austria and Switzerland. And so more than 90% of all Germans believe, that there is only one German language.
But people living in Switzerland and in Austria are exposed to their own language and additionally also to the German variation of German language every single day in their live. They all are multilingual: They actively use either Swiss or Austrian standard German when they write, they use the same language or a local dialect when they speak, and they are also very fluent in German German.
And because every German native speaker outside of Germany is exposed to German German all the time, there is nothing like an idiom or a saying "that almost every German has heard before, but no one else outside of Germany". This just is not possible. If almost every German has heard it, then also almost every other German native speaker outside of Germany has heard it.
The saying "Aus einer Mücke einen Elefanten machen" is very well known also in Switzerland and also in all parts of Austria and in all other countries where people speak German.
But, as explained before, the opposite is not true: Many sayings and idioms used in Switzerland and Austria are only know in these countries.
But we German native speakers living outside of Germany have another "problem": We don't know, which of the sayings and idioms that we use very often are well known in Germany and which are unknown there. "Our" idioms and sayings are as normal to us as those that are well known in Germany. For us there is no difference. There are just a few examples where this is obvious, but these examples are rare. Here are some sayings that are well known in Austria, but of which I believe (but don't know for sure) that they are unknown outside of Austria:
- Das Glück ist ein Vogerl.
Luck/Happiness is a little bird.
Meaning: Luck/Happiness can go as quickly as it comes.
This quote is from a Viennese song, and Viennese songs are not head a lot outside of Austria.
- Der hat hier kein Leiberl.
He doesn't have a shirt here.
Meaning: He has no chance here.
Outside of Austria the word Leiberl is used only in Bavaria. It means T-shirt.
But I know a lot of other sayings and idioms used in Austria of which I have no idea, if they are well known in Germany or Switzerland.