Counting characters in golang string

I wrote a package that allows you to do this: https://github.com/rivo/uniseg. It breaks strings according to the rules specified in Unicode Standard Annex #29 which is what you are looking for. Here is how you would use it in your case:

package main

import (
    "fmt"

    "github.com/rivo/uniseg"
)

func main() {
    fmt.Println(uniseg.GraphemeClusterCount("Hello, 世🖖🏿🖖界"))
}

This will print 11 as you expect.

Straight forward natively use the utf8.RuneCountInString()

package main

import (
    "fmt"
    "unicode/utf8"
)

func main() {
    str := "Hello, 世🖖🖖界"
    fmt.Println("counts =", utf8.RuneCountInString(str))
}

Have you tried strings.Count?

package main

import (
     "fmt"
     "strings"
 )

 func main() {
     fmt.Println(strings.Count("Hello, 世🖖🖖界", "🖖")) // Returns 2
 }