Now that is something I have never tried doing myself.
I was curious, so I just looked it up, and it looks like they're often referred to as "fermentation pots" and that the German term for it is "Gärtopf." So I did a search for Gärtopf that are sold here in CH, and found a few of them, such as this one at Landi:
https://www.landi.ch/shop/pfannen-u-...kel-10-l_74135
And this one, which is a bit smaller:
https://www.fieger.ch/gaertopf-5-liter.html
It looks like there are also many of them sold on Germany's amazon site (amazon.de), such as this one:
https://www.amazon.de/Hentschke-Kera...86W1X7ZC7QTMTF
(there are many more also listed on there).