I think Kefir exists in a salty edition, but I wouldn’t know any others.
(maybe very thin broth, but not exactly what I was looking for)
EDIT: Ohw wow! I learned about so many weird interesting new drinks, would not have expected this.
My husband loves tomato juice. He usually adds some salt and pepper to it. Also we have Clamato in Canada (I don’t know if this is available in America? We have to buy it at an international store where I live in Europe now).
I like V8 vegetable juice, they sell it in supermarkets here in the UK. It’s basically tomato juice but it has some celery, parsley, lettuce and other stuff blended into it too, plus I think a pinch of salt. It’s good but filling af, it’s like drinking a glass of soup lol.
Kvass or tepache might be up your alley too, though you might have to make those yourself, not sure if you can buy them pre made
You might want to try Pocari Sweat – a Japanese drink like Gatorade minus 50-60% sugar. It is branded as such because it was first marketed as a pre or post workout drink… and obviously English isn’t their first language so they didn’t really sweat over the how 2nd word of their brand will be recieved. Anyhoo, it is tad bit salty and tad bit sweet. I find it really refreshing. You might find Pocari Sweat on Amazon or nearby Asian groceries.