GitHub sponsor is donations in long term for open source projects. In this platform the repository ownership isn't transferred, and seller gets paid for every collaborator added and forked.
I don't think so. I do GitHub sponsor and i think its more sponsor then donation. The sponsor can get the reward specify by author. And one of the reward can be access to author private repository.
I think GitHub sponsor is more than donation. There is give and take between author and sponsors. Though it depends on the author to set up the reward and tier.
I believe selling a copy of your repo (software, solution, boilerplate) is more profitable than sponsors paying $2 once in a few month, and thats why I built this.