Onana had a mixed debut for Trabzonspor on Sunday, making an error before being named man of the match in a defeat at Fenerbahce.
Kameni believes Onana made the right decision to leave Manchester United, where he faced criticism and struggled to play last season.
“Andre was under a lot of pressure at Manchester United, and it was hard for him to get game time,” Kameni said.
“I think it's better for him to be a starter at a good club in a good league than a backup at a big club in a big league.”
Kameni also thinks Onana will be under less pressure in Turkey, where he can showcase his skills and potentially attract the attention of another major European club.
“Andre is a very professional goalkeeper, and if he has a good season in Turkey, he'll be in demand next summer,” Kameni said.