Osei-Nketia, the son of 100m national record holder Gus Nketia, attended the development camp being run by New Zealand Rugby (NZR) as part of a programme to entice athletes from other sports into sevens.
"I've never seen an athlete (like him) walk through our doors in rugby. And we probably never will see one again," NZR high performance sevens talent ID manager PJ Williams told Stuff Media.
Osei-Nketia ran for New Zealand in the 100m at the world athletics championships in Doha in September, and the 1.90m tall 18-year-old, who weighs 95kg, is concentrating on athletics for the foreseeable future.
While he has no plans to switch to rugby sevens for next year's Tokyo Olympics, longer term he is ruling nothing out.
"I'm here trying to learn more as I go as a sprinter, learn the game, learn the people and learn as many different things about rugby as possible so that one day, if possible, we can make a switch and I can be on top of the game," he said.
"We'll take it one at a time at the moment but I would love to do both," he added of potentially competing in both rugby sevens and athletics at the 2024 Games in Paris," added Osei-Nketia, who has a personal best of 10.19 for the 100m.
The teenager was the subject of a tug-of-war between New Zealand and Australian athletics earlier this year after he won the Australian 100m title following his family's move across the Tasman Sea two years ago.
However, he chose to represent the country of his birth and then relocated to New Zealand to attend secondary school in Wellington.
His father left Ghana following the 1990 Commonwealth Games in Auckland. He ran for New Zealand at the Commonwealth Games in Canada four years later, where he set the national record of 10.11 seconds, and the 1996 Atlanta Olympics.
