Stimulus Checks for dependents

I claimed my 25 year old as a dependent as he was in school for 2018 I did not claim him in 2019.. He started working and filed his taxes for 2019 which were held up due to a problem and the pandemic. He finally received his 2019 taxes back direct deposit in October 2020. He never received a stimulus check. Can he apply for it on his 2020 taxes and get it back and will he have the same problem for the 2nd stimulus check?
I also claimed my 23 year old who was in school who did not get the stimulus cause of his age which I understand. However, if he files his own taxes for 2020 and he is not on my taxes, will he be entitled to get either stimulus check thru his taxes with the IRS?