Bukhari

Hadith Footnote:
Those who are mentioned in the verses of Surah An-Nisa: “Except for the oppressed among men, women, and children...” ().

Hadith Commentary:
(1)
In the Noble Qur’an, those who, after embracing Islam, did not migrate from Makkah to Madinah have been given a severe warning. However, one group has been exempted from this warning. Allah, the Exalted, says:
﴿إِلَّا الْمُسْتَضْعَفِينَ مِنَ الرِّجَالِ وَالنِّسَاءِ وَالْوِلْدَانِ لَا يَسْتَطِيعُونَ حِيلَةً وَلَا يَهْتَدُونَ سَبِيلًا ﴿٩٨﴾ ﴿فَأُولَـٰئِكَ عَسَى اللَّـهُ أَن يَعْفُوَ عَنْهُمْ ۚ وَكَانَ اللَّـهُ عَفُوًّا غَفُورًا ﴿٩٩﴾) (an-Nisa: 98, 99: 4)
“Except for those men, women, and children who are truly weak and helpless, and who can devise no plan nor are able to find a way out—perhaps Allah will pardon them, for Allah is ever Pardoning, Forgiving.”

(2)
In the hadith, the weak people referred to are the same as those mentioned in this noble verse.
From this, it is understood that Ibn Abbas (radi Allahu anhu) was among the weak Muslims along with his mother, Lubabah bint al-Harith (radi Allahu anha), who had embraced Islam in Makkah, but the polytheists prevented them from migrating. It is evident that in such circumstances, a child follows the religion of his parents, because Abbas (radi Allahu anhu) only became Muslim after the Battle of Badr.
Since Islam is always superior and never subdued, if a non-accountable (ghayr mukallaf) child becomes Muslim, his Islam is valid, and if he dies in this state, his funeral prayer will be performed due to the blessing of Islam.
This is the objective of the chapter heading established by Imam al-Bukhari (rahimahullah) and the ahadith he has presented.
And Allah knows best.