There is a zig repo: exercism/zig: Exercism exercises in Zig. (github.com). I don’t know the state of the track but most tracks on exercsim is maintained by contributors so it means to get a language to the platform there have to be individuals who put in the time. I don’t know if the zip maintainers are looking for help, but if you got the time it is always worth asking if they need any.
The website grabs all the language repositories set as “active”. If you would want to add zig to exercism. I recommend trying to help on the exercism/zig: Exercism exercises in Zig. (github.com) repo. Since when that is up to standrad will likely that track be published. And forking the website is probably possible but seems like a lot of work.