My simple UUID suggestion made originally in https://www.reddit.com/r/golang/comments/vm51cr/is_it_bad_to_use_short_20_chars_random_strings_as/

uuid.go

package main

import (
	"crypto/rand"
	"encoding/base64"
	"fmt"
)

type UUID []byte

func (uuid UUID) Base64() string {
	return base64.URLEncoding.EncodeToString(uuid)
}

func (uuid UUID) String() string {
	bytes := []byte(uuid)
	return fmt.Sprintf("%x-%x-%x-%x-%x", bytes[0:4], bytes[4:6], bytes[6:8], bytes[8:10], bytes[10:])
}

func main() {
	uuid := UUID(make([]byte, 16))
	rand.Read(uuid)
	fmt.Printf("bytes, (storage size) len 16: %d\n", uuid)
	fmt.Printf("base64, len %d: %s\n", len(uuid.Base64()), uuid.Base64())
	fmt.Printf("string, len %d: %s", len(uuid.String()), uuid)
}

bytes, (storage size) len 16: [16 162 10 71 21 16 37 138 163 238 203 173 61 142 43 249]
base64, len 24: EKIKRxUQJYqj7sutPY4r-Q==
string, len 36: 10a20a47-1510-258a-a3ee-cbad3d8e2bf9