I think it would be great to use GitHub Sponsors for Crystal and many shards written in Crystal like Kemal, Amber, Lucky and even less popular.
There is a GitHub Sponsors Matching Fund
To supercharge community funding, GitHub created the GitHub Sponsors Matching Fund, which matches up to $5000 USD total per sponsored developer in their first year, or 12 months, of sponsorship.
Potentially smaller projects can benefit more from Matching Fund.
During the matching period, GitHub will not charge any fees, so 100% of sponsorships will go to the sponsored developer. In the future, we may charge a nominal processing fee.
To be eligible for the GitHub Sponsors Matching Fund, you must apply to GitHub Sponsors by January 1, 2020.
Sadly the list of supported countries is quite limited, see Setting up GitHub Sponsors for your user account