My friend's great-grandmother is German. Will it be relatively easy for him to immigrate to Germany?

Germany is a non-immigrant country. Legally speaking, it is impossible to immigrate to Germany directly, which has nothing to do with whether their relatives are Germans or not. However, if relatives are in Germany, it may be easier to apply for a visa. For example, they have studied or worked in the past, and it may be easier to get a visa if they have relatives to take care of them (provided that all the requirements of this visa type are met, of course). Many people want to stay after the past, and Germany cannot immigrate directly.