monorepo和自定义目录结构中的多个Go模块

I have 2 possibly related issues.

I have a test monorepo setup, with 2 subdirectories (mod1 and mod2).
Each one of them has a go.mod file in them, and each of the modules has a single .go file with basic printing code. in mod2 there is a subdirectory mod2_lib (that holds one of those simple .go files with basic printing code), since I read that Go modules are basically their own little GOPATH's.

Id like to call function Run() thats in a package mod2/mod2_lib from mod1, but all Im getting is build github.com/account_name/test/mod1: cannot find module for path github.com/account_name/test/mod2/mod2_lib.

here are the files Im using to figure this out:

mod1/t.go

package main

import (
    "fmt"
    "github.com/account_name/test/mod2/mod2_lib"
)

func main() {
    fmt.Println("mod1")
    mod2_lib.Run()
}

mod2/mod2_lib/t_lib.go

package mod2_lib

import "fmt"

func Run() {
    fmt.Println("RUNS")
}

the second issue is that in this monorepo I'd like to have related Python and Rust code in top-level dirs py and rust. So I'd like to place all my Go packages in the go/src dir. How would other people import this go/src path into their project (possibly still having the "github.com/account_name/test/mod2/mod2_lib" as the import path, and not "github.com/account_name/test/go/src/mod2/mod2_lib")?

can anyone give me some pointers on these issues? I want to move to using Golang modules, and abandon the GOPATH.

the issue was that it was a private github.com repo. making it public fixed it! :) have to figure out authentication now for the module system.