是的，使用泛型是可能的。为函数的2个返回类型使用2个类型参数：

func runFunctions[T1, T2 any](
    f1 func() (T1, error),
    f2 func() (T2, error),
) (res1 T1, res2 T2, err error) {
    var wg sync.WaitGroup
    wg.Add(2)

    var err1, err2 error

    go func() {
        defer wg.Done()
        res1, err1 = f1()
    }()

    go func() {
        defer wg.Done()
        res2, err2 = f2()
    }()

    wg.Wait()

    // check errors
    if err1 != nil {
        err = err1
        return
    }
    if err2 != nil {
        err = err2
        return
    }

    return
}

注：

• 使用defer调用wg.Done()
• 必须检查wg.Wait()之后的错误!

使用它也变得更简单，因为你不必处理类型Assert：

func main() {
    defer timeTrack(time.Now(), "Fetching products with sizes")
    fmt.Println("Starting synchronous calls...")

    client := &Client{}

    prodModel, sizesModel, err := runFunctions(client.GetProduct, client.GetSizes)
    if err != nil {
        // return error
    }

    build(prodModel, sizesModel)
}

这将输出（在Go Playground上尝试）：

Starting synchronous calls...
product 123 has size S
product 123 has size M
product 123 has size L
2009/11/10 23:00:05 Fetching products with sizes took 5s