It’s to promote youth soccer. They’ve done it as long as I can remember. I don’t think it’s anything nefarious although FIFA is corrupt as hell so who knows

Back in the days when sports loved the fans. A MODEL would escort the players on to the field.

I don't watch but you made me interested. Saw this explanation and my take is it probably is fronting for other things because as it explains it was to raise awareness for 'charitable' organizations which tend to be perpetrators of child trafficking. Also the tradition started in Liverpool....

https://www.liverpoolecho.co.uk/news/liverpool-news/revealed-how-paedophile-monster-jimmy-10950880

Kids who walk out with the players are known as "player escorts" or "mascot children," and they have been a part of football matches for over 20 years. After a match between Liverpool and Everton in November 1996, one of the first images of children strolling as mascots was featured in the Liverpool Echo. Beginning about the year 2000, the practice of having one escort for each player, rather than simply one or two each squad, began.

Early on, having kids accompany the players doubled as a means to generate awareness for charitable organizations. Before the 2002 FIFA World Cup, FIFA and UNICEF collaborated on an initiative called 'Say Yes For Children' "to promote and protect the right of all children to healthy recreation and quality primary education," according to a UNICEF press release at the time.

"Children are being given a prime role at each match, accompanying each player on to the pitch in a symbolic action reminding football enthusiasts that they have a major role to play in building a world fit for children," the statement read.

https://www.dnaindia.com/sports/report-why-do-kids-accompany-football-players-when-they-come-out-and-when-did-the-mascot-tradition-started-3005901

You intuition is correct.

They've always done it. Do it at premier league and champions league games too.