Yes, he could since he won in 2022 and 2023. When i mean the right circumstances, i mean if his progress hadn't been delayed due to health problems. Nevertheless he was second when he didn't achieved the progress he could had done in 2021.
Sure, and Riccardo Riccò would have won the 2008 Giro if he had been as strong as he was in the Tour. Pogačar would also have won the 2019 Vuelta if he had his TdF 2021 legs.
There's a big difference between reaching your highest level yet and reaching your absolute peak. Vingegaard wouldn't have been as strong in the 2022 Tour, if he hadn't experienced the 2021 Tour beforehand.