LinkedIn is a good place to start. It’ll help you in building a network. But even if they write and send it to you on Github, or anywhere public, it would be considered. Your Github projects can have a place for raising PRs/Issues as recommendations or review. Point is it should be in public

What if I couldn’t find anyone around for review/recommendation? Am I going to be eligible?

See we already have 20+ mentors. Once I start publicizing we’ll get more. You will have enough people to review. Don’t worry. Worst case, you’ll have to ask the other participants or in social media. I would say focus on completing the 5 plus 3 first, then worry about the 2. By the time you reach to the 2, you’ll have enough reach and someone will definitely review or recommend you. Keep sharing your progress on social media. So, if you complete 5 plus 3, I’ll guide you to get the rest 2.