Does the verse, "And you were on the brink of a pit of Fire, and He saved you from it," indicate that whoever was sincere in their intention to search for the true religion but was not guided to Islam will end up in Hellfire?

The noble verse, "And you were on the brink of a pit of Fire, and He saved you from it," does not mean that Allah saved them because of their sincere intention, but rather by His grace, or because He knew there was good in them. This verse was revealed concerning the Aws and Khazraj, who were enemies in the pre-Islamic era (Jahiliyyah). Allah united their hearts through Islam and saved them from disbelief, which leads to the Fire. A Muslim should not preoccupy himself with the fate of those who died upon disbelief, but rather concern himself with saving himself from the Fire.