The chicks will not need grit to eat hard boiled eggs. Their system will be able to handle the whites and the yolk. That's one thing you don't have to worry about.
The chicks may or may not be very hungry. They can live off of the yolk for over 72 hours so if they are just 2 days old they still have nutrition available to them from the absorbed yolk before hatch. It will not hurt them at all to eat something. I'd consider it a good thing if they did, just not a necessary thing. An egg, especially the yolk, would be a great food for them. That's what they absorbed and are living off of. The yolk is about 1/3 fat, which would give them great energy. The rest is full of nutrients. It should get them off to a great start.
Once they settle in you want the majority of their food to be the chick feed so they get a better balanced diet. The chick feed contains a more varied mix of nutrients. But to get them off to a good start I can't think of anything better than egg, especially egg yolk.