Implant pain, questions about precautions

I heard that the typical duration for an implant is about 5 to 6 months. Is the pain usually very severe?

I am curious about how it compares to general dental treatments (gum treatment, cavity treatment).

In the case of a person with very weak health (low body weight and poor immunity) receiving an implant

I'm also worried about whether there might be any dangerous or problematic parts.