However, given sourcehut eschews the use such "social metrics" (which at some level I agree with the principle behind it, on the other hand I do appreciate the value of being able to give visibility to good projects) I usually mention in my README that "If you like the project and wish to promote it, feel free to star this github page".
I'm sure github probably wouldn't like this use-case, but the stars would certainly be genuine, even if possibly quite dodgy-looking.
It's still getting starred...