Grapevine doesn't seem to be similar to Meta or X to me.
Ads can definitely be done but might be difficult to scale as privacy-conscious anonymous users might not share their preferences. Or they might, I don't know anything about anonymous users.
Charging users for usage also seems tricky as most of us don't share valuable, premium content (like Medium) but do tons of shitposting (like Reddit). Maybe charging users for premium services could be one avenue?
Grapevine feels closer to Blind or LinkedIn so monetization can be inspired by them. Maybe charging companies is the likeliest way? Recruitment and careers solutions for employers and/or candidates could be one avenue.