The thing to note about Amazon or Google making agreements to buy energy from nuclear reactors that haven't been built yet is that nuclear reactors are either megaprojects that take 10-20 years from plan to completion or vaporware with untested designs and uncertain timelines and are unlikely to come online before 2035. Even extending existing reactors, theoretically the simplest kind of these projects, often run over on time and budget and end up taking a decade to get running