Replacing the kidnapped

Greetings to the Rabbi!
Journalist Shaul Mayzlish raised the option that he and other people would exchange the children kidnapped by Hamas, for details see the attached article:
https://www.inn.co.il/news/620121
It is indeed very theoretical and it is doubtful how realistic it could even be, but in this period when reality surpasses all imagination and it is no longer possible to know exactly what to expect – is it halakhically acceptable for a person to put themselves at risk in order to save someone who is at higher risk? Does the value of an adult versus a child come into play here in the halakhic system of considerations? I admit that intuitively the possibility that Shaul Ma’aleh raises does not seem halakhically possible to me. But I would like to know what the rabbi’s opinion is on this possibility.