database dump encoding

When I make backup of database whether by this plugin or by another backup plugin I get the sql file with rigidly set UTF8 encoding, as I understand. So for example unicode symbols like emoji get lost. They all get transformed to ? sign.
As I understand encoding should be utf8mb4.
So I checked that in wp-config.php I have utf8mb4 is set.
And on the server side in the mysql config file I have

[mysqld]
init_connect = ‘SET collation_connection = utf8mb4_general_ci’
character-set-server = utf8mb4
collation-server = utf8mb4_general_ci
[client]
default_character_set = utf8mb4

Furthermore if I make dump in the server console like so

mysqldump -u username -p -dbname > file.sql

I get target encoding utf8mb4 and then by upload this sql file to test server emoji symbols don’t get lost.

So I found on github mysqldump php library here https://github.com/ifsnop/mysqldump-php
I’m not so experienced in php development but I didn’t found the way to change encoding by class constructor. Of course I doubt that exactly this library is used php installed in the server. May by you use your own library.

So may be it worth to considerate include this option to change encoding. In premium version of the plugin ?? It will be a feature which other plugins don’t have.

I hope what i wrote isn’t total nonsense. May be I’ve done something wrong.
Just really want to get things right for me and understand how it works.
Thank you in advance.