Based on certain verses, like Surah al-Tawhbah, verse 111, and Surah al-Saff, verse 10, it is understood that Almighty God forgives the sins of a martyr who dies in the path of God. The martyr will be blessed with the everlasting abode of heaven because of their sacrifice.
Of course, we know that not every person will have the great opportunity of dying in the path of Allah, and it is indeed something granted by the Almighty to only those who deserve it and have spiritually worked for it.
We also have traditions that refer to certain individuals who will enter Heaven without being judged, and there are plenty of such cases.
If the martyr has certain obligations towards others, or a debt, or something like that, then that would also not be in conflict with them entering heaven.
And Allah knows best.