I'm not a typst user but from a quick look at the language you should be able to type C\#

You can also write a macro

#let csharp = [C\#]

And then use it as #csharp

Or even `#show "csharp": [C\#]` and then just write `csharp`. Though then you couldn't include the actual text "csharp" in your document, should you wish to, so perhaps defining the variable is a better option.

Thank you! I don't know how or why this works but on my computer, turns out I can skip the square brackets which I tried out after seeing your answer.

    #let csharp = "C#"

for some reason this works and does not throw an error. so now I can use it like

    == Technical Skills
    - *Languages:* #csharp, JavaScript, TypeScript, Python, SQL, Ruby, Java, Kotlin, Rust, Go, PHP

C\#