The EU cannot force anything. It would be enough for the company that provides WhatsApp to not have any business in the EU (today that's FB, it could be a spinoff tomorrow).
The only, weak, solution would be to force the EU ISPs, on an European level, to block FB. Blocking on itself will not be easy (technically speaking) and good luck to have a consensus on that among our countries.
I completely fail to understand why many US companies, operating on US grounds care about GDPR at all. I would not and, please, sue me. Even the ones that block access from EU are overreacting.
The only, weak, solution would be to force the EU ISPs, on an European level, to block FB. Blocking on itself will not be easy (technically speaking) and good luck to have a consensus on that among our countries.
I completely fail to understand why many US companies, operating on US grounds care about GDPR at all. I would not and, please, sue me. Even the ones that block access from EU are overreacting.