$ mongo --host 192.168.64.6
MongoDB shell version v4.0.3
connecting to: mongodb://192.168.64.6:27017/
Implicit session: session { "id" : UUID("e4d7cea2-ab81-45ad-a51e-e7acf45a7242") }
MongoDB server version: 4.4.8
WARNING: shell and server versions do not match

mongos> use testing
switched to db testing
mongos> db.numbers.find()
{ "_id" : ObjectId("61b71d3d73b251bceee62032"), "type" : 0, "value" : 0 }
{ "_id" : ObjectId("61b71d3d73b251bceee62033"), "type" : 1, "value" : 1 }
{ "_id" : ObjectId("61b71d3d73b251bceee62034"), "type" : 2, "value" : 2 }
{ "_id" : ObjectId("61b71d3d73b251bceee62035"), "type" : 3, "value" : 3 }
{ "_id" : ObjectId("61b71d3d73b251bceee62036"), "value" : 4, "type" : 4 }
{ "_id" : ObjectId("61b71d3d73b251bceee62037"), "value" : 5, "type" : 5 }
{ "_id" : ObjectId("61b71d3d73b251bceee62038"), "type" : 6, "value" : 6 }
{ "_id" : ObjectId("61b71d3d73b251bceee62039"), "type" : 7, "value" : 7 }
{ "_id" : ObjectId("61b71d3d73b251bceee6203a"), "type" : 8, "value" : 8 }
{ "_id" : ObjectId("61b71d3d73b251bceee6203b"), "type" : 9, "value" : 9 }
mongos>​

package main

import (
	"context"
	"fmt"
	"time"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"gopkg.in/mgo.v2/bson"
)

func main() {
	// init mongodb client
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://192.168.64.6:27017/"))
	if err != nil {
		fmt.Println(err)
		return
	}

	// mock some data
	collection := client.Database("testing").Collection("numbers")
	for i := 0; i < 10; i++ {
		_, err = collection.InsertOne(ctx, bson.M{"type": uint8(i), "value": i})
		if err != nil {
			fmt.Println(err)
			return
		}
	}

	// query
	filter := bson.M{"type": bson.M{"$in": []uint8{1, 2, 3}}}
	res := collection.FindOne(ctx, filter)
	if err = res.Err(); err != nil {
		fmt.Println(err)
		return
	}
}
​

go run main.go

(BadValue) $in needs an array​