Punishing companies directly that do business with Facebook/Meta would probably be the strongest deterrent. If we can sanction countries, why not companies?
That's how sanctions are usually implemented. See: Russia and Iran, trickling down to their state businesses and armaments industries, tricking down to their suppliers. The only difference here would be there isn't a nation-state as the starting point.
Yup. That's what I meant too. The Iranian Revolutionary Guard Corp doesn't care much about US sanctions, but other companies selling them {insert thing} do, if it has financial repercussions.