Ighalo scored 16 goals in 35 appearances for Nigeria before retiring from international duty after the 2019 African Cup of Nations.
The 30-year-old also represented Nigeria at the 2018 World Cup in Russia.
A deadline day loan move to Old Trafford from Shanghai Shenhua shocked the football world.
Some have suggested Ighalo's move back to the Premier League could prompt Nigeria manager Gernot Rohr to persuade him to return to the national team set-up.
But Fati Amoo, who coached Ighalo in his early days at Nigerian club Julius Berger, says people in his homeland think the striker should allow younger players to flourish for the Super Eagles.
Asked about how Ighalo's move to United was received in Nigeria, Amoo told Tribalfootball.com: "Generally in Nigeria, the news of Odion joining Manchester United has been well received with great optimism.
"If I calculate the percentage, I think it is 90% approval rating of the news that he signed for Manchester United.
"Most Nigerians everywhere are happy. If you hear the comment on radio, the reports in the newspaper and Nigeria's online news websites, the reactions have been favourable, like a thumbs up to Man Utd for signing him.
"The only thing is that, some Nigerians don't want him to come back to the Super Eagles, so that the young players he left in the team can continue to develop and improve, but overall, it is a welcome development.
Born and raised in the tough Lagos neighborhood of Ajegunle, Ighalo is a boyhood United supporter.
He will become the first Nigerian to play for the Red Devils when he makes his debut.
And Amoo says people in Nigeria are immensely proud of Ighalo.
"His decision to retire from the Super Eagles is best known to him. He was in the team for some years before he took the decision.
"It will be good for Nigeria football if he succeeds in Manchester United. You know Wilfred Ndidi, Kelechi Iheanacho, Alex Iwobi all doing well in England and Nigerians are always excited, happy when they play well for their clubs in Europe.
"So if Odion becomes the answers to some of the goalscoring problems of Man Utd as highlighted by Ole Gunnar Solskjaer, of course Nigerians will be very happy. There are many Manchester United fans here in Nigeria. It will definitely bring many positives to Nigeria football and Manchester United can also look further towards the direction of having more Nigerian players to sign for the club.
"That is my prayer and the prayer of many Nigerians that he should succeed and open the doors for more Nigerians to play for Manchester United."