The 18-year-old winger's development is closely monitored in Australia after transferring to German giants Bayern Munich from Adelaide United.
A number of Australian prospects have struggled to make the grade in Europe, including 19-year-old winger Garang Kuol who signed with Newcastle United two years ago but has yet to play a senior match with the Premier League side.
"It's the last thing you want for (Irankunda), and the fact that Bayern have kept him on is a very positive sign, rather than loaning him out," Arnold told Australian media on Wednesday.
"I’ve seen players in the past that everyone was talking about, drooling about, and then all of a sudden they can’t deal with the pressure, they can’t deal with headlines, and all that stuff.
"But I think Nestor will be fine. I’m excited to coach the kid. I just want what’s best for the kid, and we make sure that we get the right people around him, which is important because, again, he’s only 18."
Irankunda scored twice and had three assists in the pre-season for Bayern after making his international debut against Bangladesh in June.
In his second Australia match against Palestine, he became the second-youngest player to score for the Socceroos.
Ahead of Thursday's World Cup qualifier against Bahrain, Arnold said Irankunda's time training at Bayern with the likes of Harry Kane and Thomas Muller had already paid dividends.
"Mentally, you can see there’s a bit more belief,” he said.
"He actually feels he belongs because he’s been training with those players and he sees that he’s at the same level.
"Physically, obviously, he’s still a kid, he’s got a lot of work to do."
Arnold said he had yet to decide how to deploy Irankunda against Bahrain as the Socceroos look to kick off the third phase of Asian qualifying for 2026 with a win on the Gold Coast.
However, he was looking forward to seeing what the winger could offer.
"Obviously he can have a massive impact off the bench, maybe when the legs start going out of the opponent, but he’s also someone that can start and get us a goal early," said Arnold.