New Social Link Icons

Thank you for a great theme. But can you please give me some help with two questions:

1. Can you add some new social link icons?
2. Is this possible to have additional user-defined social link icons?

I really missing:

• vk.com
• patreon.com
• buymeacoffee.com
• Telegram

Now it looks like this.
The icons for vk.com, patreon.com and for buymeacoffee.com are the same default. Twenty Fifteen doesn’t have any special icons for them.
I tried to add something in my child theme but I didn’t find any ways for that.

I read https://www.ads-software.com/support/article/twenty-fifteen/ . It lists the supported social media. But are there any ways to add some new?

The page I need help with: [log in to see the link]