Florian Fangohr waffled for about a year over whether to buy an Apple Watch SE as a gift. The smart watch cost $279, and he worried that its recipient would immediately break or lose it. In May, he decided the benefits outweighed the costs and bought the gadget.

The beneficiary: his 8-year-old son, Felix.

Mr. Fangohr, a 47-year-old product designer in Seattle, said he was aware that many people were pessimistic about technology’s creep into children’s lives. But “within the framework of the watch, I don’t feel scared,” he said. “I want him to explore.”

Felix, a rising third grader, said he actually wanted a smartphone. “But the watch is still really, really nice,” he said.

Across the United States, parents are increasingly buying Apple Watches and strapping them onto the wrists of children as young as 5. The goal: to use the devices as a stopgap cellphone for the kids. With the watch’s cellular abilities, parents can use it to reach and track their children, while the miniature screens mitigate issues like internet addiction.

Children and teenagers appear to have become a disproportionately large market for smart watches as a whole. In a 2020 survey of American teenagers by the investment bank Piper Sandler, 31 percent said they owned a smart watch. That same year, 21 percent of adults in the United States said they owned one, according to the Pew Research Center.

The use of smart watches as a children’s gadget shows how the audience for a consumer technology product can morph in unexpected ways. It has also given new life to the Apple Watch, which was unveiled in 2015 and has been variously positioned as a fitness tracker, a style statement or a way to free yourself from an iPhone.

Apple has deliberately turned the watch into a device that can be attractive for children and their parents. In 2020, the company released the Apple Watch SE, which had fewer features than a premium model and was priced $120 cheaper. Apple also introduced Family Setup, software that let parents track their children’s locations, manage their contacts list and limit their notifications.

The Silicon Valley company’s moves to make the Apple Watch a child-friendly cellphone took about three years, said two people involved with the project, who were not authorized to speak publicly. A chief concern was battery life, since the watch used more power when it functioned independently from an iPhone, they said.

Apple plans to compete more aggressively soon for young smart watch customers. At an event on Wednesday, it is set to release a new version of the Apple Watch that is cheaper than the Apple Watch SE, the two people said. The model will be introduced alongside other new versions of the watch, including a high-end wearable for serious athletes that will rival fitness trackers made by its competitor Garmin, they said.

Apple referred to a statement from Jeff Williams, the chief operating officer, who said, “For family members who do not have an iPhone, Apple Watch offers a remarkable set of features that can help them keep in touch with loved ones, be more active and stay safe.” The company declined to comment on the new watches at its coming event.

Apple does not break out sales of the Apple Watch. To date, there are at least 120 million Apple Watch users — most of them in the United States — according to estimates by Counterpoint Research. In China and South Korea, Huawei, Xiaomi and Samsung have also rapidly increased wearable sales among young people.

Any technology used by children raises questions of risks and harms. Social media platforms in particular have faced scrutiny in recent years, with lawmakers holding congressional hearings on the issue in 2021 and homing in on whether sites like Instagram led to poor self-esteem among teenagers.

Jean M. Twenge, who writes books on how tech contributes to generational differences, added that the longer that parents could hold off on providing children with a smartphone — and increased accessibility to social media and other internet wormholes — the better.

Receiving a smartphone later means children “will be older, more mature and more able to handle the challenges and potential dangers of having their own smartphone,” she said.

Still, buying a smart watch for children can hook them to technology early. When young people use a product, they tend to remain loyal to the brand as they grow up and become working professionals, analysts said.

Jon Desi and his wife recently used an Apple Watch SE as training wheels for a smartphone for their daughter, Catie, when she was 10. When she started playing outside more at the beginning of the pandemic, they couldn’t find an “old-style phone” so their daughter would have more freedom to venture around their neighborhood in Hunt Valley, Md., they said. They settled on the Apple Watch instead.

“We wanted to give her a way to communicate without giving her Pandora’s box at the age of 10,” Mr. Desi said.

But the watch came with a stipulation: Catie had to charge it and wear it regularly, answer when they called and text back in a reasonable amount of time to receive a smartphone.

It became “the carrot to enforce responsible behaviors,” Mr. Desi said.

In July, he and his wife purchased an iPhone for Catie, now 11, and handed her Apple Watch down to their 10-year-old son, Tommy. When their 5-year-old daughter, Ellie, is older, they anticipate handing down the Apple Watch again.

A smart watch is not a guaranteed delay to a cellphone. Todd Golub and his wife, who live in New York City, gave an Apple Watch SE to their son Ronan when he was 10, as he began exploring the city by himself. The watch was more difficult to break and lose than a phone, and Ronan used its mobile wallet to pay for food and public transit.

But last fall, they bought an iPhone for Ronan, now 12, when he entered middle school because all his schoolmates had smartphones. Mr. Golub, 49, said he would have preferred to introduce a smartphone at least a year later but worried his son would feel like he was missing out.

“Should I have pushed that out further? Yes,” he said. “But I remember being their age.”

Now Ronan often forgets to charge and wear the watch. The watch, Mr. Golub said, is “almost irrelevant.”