"We did not get the result we wanted and we leave the competition sooner than expected," Ronaldo admitted as his side failed to match their 2016 exploits.
Despite having just 2,500 tickets for the 22,500 crowd limited by coronavirus restrictions, Scottish fans have already descended on London in their thousands.
He has regularly spoken about his desire to win trophies, but is yet to land one with Tottenham, who are without major silverware since the 2008 League Cup.
The government has signalled the relaxing of restrictions will be staggered over a period of months after a hasty reopening in late 2020 contributed to a surge in cases.
"I'm sure that we will open the European Championship in Rome and that we will do it with a crowd in the stadium," Gravina told a news conference on Friday.
"I still don't know how many spectators there will be, but there will definitely be a crowd."