如何在go中动态更改函数参数类型

I have a program as below. I am trying to change the type of a function argument dynamically as another library I am using requires passing myMethod signature with concrete type instead of that interface to do proper unmarshalling. Is that even possible in Go to dynamically make a function or anonymous function with argument's type generated dynamically or perhaps change the parameter type of a function?

package main

import (
    "fmt"
    "reflect"
)

type MyType interface {
    doThis()
}

type MyType1 struct{}

func (m MyType1) doThis() {
    fmt.Println("Type1 doThis")
}

type MyType2 struct{}

func (m MyType2) doThis() {
    fmt.Println("Type2 doThis")
}

func myMethod(myType MyType) {
    myType.doThis()
}

func main() {
    fmt.Println("Hello, playground")
    var type1 MyType
    type1 = &MyType1{}
    type1Val := reflect.TypeOf(type1)
    // TODO - change myMethod signature dynamically to accept type1Val as the type
}

Here is the GoPlay link

Edit: Adding clarification

The library I am using exposes a registerSomething(someFunc) where the input argument type of someFunc will be later used in some unmarshaling. If the input argument type is an interface, the unmarshal will return a map. If its a typed struct, the unmarshal will return the typed struct with all params populated correctly so I don't have to deal with unmarshaling.

How to change function parameter type dynamically in go [?]

You simply cannot. Go is statically typed.

(Making your code run is trivial, but probably not what you want:

type1Val := reflect.ValueOf(type1)
myMethod(*(type1Val.Interface().(*MyType1)))

and I have to admit I do not understand what you are trying to do with reflect here.)