This is not a clickbait questioning title with an answer post. It is a genuine question to ask, and this post is going to continue elaborating the question. Sorry if you came here for an answer. Do stay if you are interested or are in the similar situation or is my answer.

Let us not bother about the kind of cooperation first. It can be co-founding, full time employment, part-time remote, hourly rate freelancing, or project base contractor. Focus on how to reach the right individual now. 

Where, will this individual be, physically or virtually, that we can search and query? Many posted their projects and open source contribution on GitHub. Many list down their working experiences in LinkedIn. Few become influencer in Twitter and TikTok. Few wrote helpful contents and post it as blogs.

Many, many more, are lurking in the corner of a chat room. Some only like tweets. Some only read feeds. Some never post anything. But these might just be someone that is right for me too. Though, unreachable.

Job post? Spam Reddit? PM random people on Twitter who replied to a tech post?

Scan GitHub profile and project? Filter freelancer on Upwork? Email ex-colleague? 

Email the world with Hey? I think I will start with this.