I think 2 great community activity indicators are - Github issues and of slack/discord/discourse comments. One key thing with github issues in my opinions is that, If the github issues are mostly by the core team, it is not a great sign. You want a large mix of issues from customers or users and not from the team. This is a good indicator if the project is solving real problem or not. Stars is very low threshold action. Same goes with the slack comments, it should have both volume and freshness.
Also if you get "smart" and donate on multiple cards, I would think it is a trivial task for github to determine is is a scam. The CC address would match you Address for the funds your receive.
Probably way too much work for this :)