Well in case of zig the current job market is non existent. And for Go there is definetly a job market. It however always depends on your location. Just like there are areas with 0 to no Go positions available, there are areas with (almost) no Java positions. Same applys to every other language.
Zig or Go are serious programming languages. Zig is actually the language I would least recommend for complete beginners because in my opinion it is one the most serious languages currently. What lead you to your examples Zig and Go and how do you determine what a ‘serious’ programming language is?
No but you can lie to yourself that you are.
Just out of curiosity, what is such an API used for?