George had a tremendous backlog of संगीत that he basically put into his first solo post-Beatles, which was a TRIPLE album. Some of his best music, in my opinion, were on this album. However, like Paul, his संगीत missed John's middle eight bars, which distinguished many Beatle hits.
But, to answer the question...YES, George could have and should have sung और than the ONE song he was allowed per Beatle album.
NO, Ringo sang just enough on the songs that were written for him. Need proof? Check out the writers, backup artists and vocals on the three songs he put out after the Beatles breakup and you'll get the point.
Well, yes, I do. But I know John and Paul did their best to make sure George and Ringo got to sing some songs. And when आप consider how many bands just have one lead singer and no one else sings anything....