It depends on the sport really. In some sports it doesn't make a difference, but in some it does.
Artistic Swimming: I think it possibly helped because we qualified in the team event for the first time since 2004 and most of our girls are teenagers so it gave them an additional year to prepare.
Athletics: I think it helped some athletes here and hurt others. For example Tentoglou now seems to be a favourite to win a medal in Tokyo, but I'm no longer confident in Stefanidi. Kyriakopoulou and Papachristou chances seem to have decreased a lot. And we have some athletes who are either definitely or probably going to miss the Olympics because of injuries in the past year that made them go down in the rankings or not compete at all (Belibasaki, Baniotis, Tsiamis, Gusin), though there were a few positives like our young race walker Filtisakou who seems to be safe to qualify. Didn't think she had a chance to make it until a few months ago.
Boxing: It definitely hurt us as our best boxer who was one win away from making it to Tokyo in 2020 got injured and couldn't compete this year when the qualification tournament resumed.
Rowing: I think it helped because our team is very young and even though it's a smaller team than usual, we have some outside chances for medals which we didn't think was possible back in 2019.
Sailing: I think it probably hurt us that 2004 gold medalist Tsoulfa came back and took the spot of Bozi/Klonaridou who had a small chance to win a medal in Tokyo. They only had a very small chance, but they totally flopped in the internal qualification (when they were the only Greek crew in the event for 5 years until now) and Spanaki/Tsoulfa don't have any chance to win a medal but "stole" Bozi/Klonaridou's quota.
Shooting: I think it was negative for us because one of our skeet shooters was in great form before covid and now he didn't qualify.
Swimming: I think it helped some athletes here and hurt others.
Taekwondo: Helped our young girl as she had an extra year but also we had a 2019 World Championships silver medalist (Telikostoglou) miss out, maybe in 2020 he would've made it.
Tennis: I think it helped. Tsitsipas and Sakkari have improved a lot.
Water Polo: Definitely hurt us. Strict lockdown rules prevented our teams from playing as the domestic leagues were shut down for several months. The women went to the qualifying tournament without having their players being in form and same with the men who almost didn't qualify. The men have more players who play in other countries, but still the domestic ones don't seem to be doing well. Olympiacos won the Champions League or made the final the last two seasons and then this year they got destroyed in the quarterfinals.
Wrestling: I think it helped because one of the two wrestlers we qualified is very young and also was injured last year.
Sports where we didn't qualify yet:
Gymnastics: I think it definitely helped Petrounias' chances. We will know in the next few days if he will qualify or not, but it gave him more time to recover from his injury.
Basketball: Horrible. Everyone is injured this year and with the NBA season running later than usual because they started late, we will be missing our two-time NBA MVP and his brother at the Olympic qualifying tournament. Usually the NBA season is already done by now.
Beach Volleyball: We still likely won't qualify our girls, but one of them tore her ACL in late 2019 (Vasiliki Arvaniti who is a three-time Olympian). When she got injured that was the end of her Tokyo dream, and then when the Games were postponed suddenly she had another chance as she had time to recover from her injury. So if they qualify then it definitely helped.