In the past few decades, some Islamic scholars have put forward the view that Dajjal is metaphorical for an evil system, such as capitalism. Others hold to the literal view in hadith that Dajjal is a one-eyed person who will arise at the end of time, have many followers, cause suffering and harm, deceive people into following him, and ultimately be defeated by the Mahdi (A). (In that, the Mahdi will be supported by Jesus (A))
It is often difficult to understand future prophecies until they happen. Certainly, many prophecies about the Dajjal would have seemed fanciful in the past. For instance, there is mention of the Dajjal having a smoky chariot that crosses great distances at great speed. However, these days, this sounds normal to us. 50 years ago, the idea that, in the end times, the believer in the east will see the believer in the west was farfetched, and yet today we can do it with mobile phones.
When it is time for the reappearance of the Mahdi (A), it will be clear. Of course, in the meantime, it is good to be cautious of things that have a Dajjal-like aspect - in particular, deceiving people and causing suffering - whether or not they are individual leaders or intangible things such as ideologies.
There are a lot of views in narrations about what Gog and Magog are. Some identify specific peoples. Some refer to them being something other than Bani Adam (i.e. not humans). Some attribute peculiar and non-human traits ot them. They are also discussed in the Jewish and Christian traditions and they also have various ideas about who they are. Some people may have been tempted to draw parallels between Gog and Magog and twentieth-century powers such as the US and the USSR; however, given that the international situation is always changing, it seems that this is unlikely. In any case, this doesn't match the Qur'anic view of them existing in ancient times and having a wall built between them (18:94-95). So, basically, this is an issue which there are many viewpoints about. For more information you can look at tafsir works on the verses of the Qur'an pertaining to Gog and Magog.