Hm I’m not sure this is a good example, it’s really just a dialect. Any German speaker can usually understand most of it when concentrating a bit. And Wikipedia seems to agree. [1]
The official written language is German, albeit a different standard than non-Swiss German. The difference is not that big, it's like between written American and British English. But I can assure you that most non-Swiss German speakers can't casually understand Swiss German dialects.
Edit: these dialect are commonly used in court, public offices, and often on TV. They have a vastly stronger role in public life than in other German-speaking countries.
That's dialects though. The same could be said for most regions in the UK from people living in the UK or abroad, e.g., a Scouse understanding a Glaswegian. This is similar in Italia across regions.
They are dialects. Swiss German isn't a language but a group of dialects, but they aren't closer to high German than Czech is to Polish.
I think my point stands that it's a distinct language from the official one. It definitely feels like that in practice where a lot swiss people feel like they have to wear their official hat when speaking regular German and they prefer to have casual beer conversation in English rather than high German.
Edit: these dialect are commonly used in court, public offices, and often on TV. They have a vastly stronger role in public life than in other German-speaking countries.