It's difficult to see from the photo how deep the impression is but if the piston is forged you can likely polish off the sharp edges and reuse it. I've seen worse. Forged pistons are very tough. I would definitely have it checked. If you can buy a single exact duplicate I would go that route because it's probably cheaper than paying a pro to rework and check that one.
I would be more concerned about the cylinder head(s). Valve seats typically don't just fall out. Cracked head, overheated, poor initial installation...?
It doesn't take long to damage bearings. You probably did not damage the rod but it's possible the bearing got pounded a little. Same for the small end.
If time or budget is an issue or you feel confident in the rest of the engine, you can deal with the piston top, have the head repaired, reassemble everything and likely be OK.
Or, go through the process of having both heads checked, removing the piston and rod and having them checked, serviced and assembled.
Mike