Every match in the main stage of the World Cup is as exciting as it is, but in the qualifying matches, there is no such excitement. Basically, the main stage matches of the World Cup create a different excitement among the spectators, due to which the performance of the players is already good, but when the qualifying matches are held and there is a match between two teams, if it is already easy for both teams to make it to the main stage of the World Cup, then those matches do not seem interesting to us. Because at that time, it seems that the big teams will definitely qualify for the main stage of the World Cup.

The reason why friendlies are not as hyped is because they are not linked to anything. The result don't matter. Winning or losing don't matter.
As the result of the game doesn't matter, teams are more willing to experiment things. Players and teams can practice their own way but friendly match makes them know more about the team they are playing with. For that teams may try to hide their specific strategies and skills in order to use them as a surprise when they play real matches.
If its a tournament they are playing be it a league or knockout, they'd give all they have to win those games.

In any case, this is something that will allow the first time to better understand the team and how the players interact with each other in combat conditions, it's better than immediately play a match in their league and do not know how the players will behave, it can banally lead to defeat, because what happens in training it is a completely different level

The issue about friendly matches is that you can never create the same tension and atmosphere for the players. It is either because your own players don't take it seriously enough or because the opponent doesn't play their best game. If you really want to know whether a certain strategy or formation works well against good teams, the only way is to find out to test it during at least the qualification games for the big international events. In friendly games you can see weird things happening that do not very well reflect what should be expected in important games.

Yes, here we need either a whole tour of friendly matches so that the coach can build a normal tactics of the game, or a few games at the official level within some tournament. Honestly it's hard for me to imagine what a new coach should do when he is expected to produce results in the first game, considering that the players are assembled a week before the national team game. What should he teach them? This is not the national championship, this is the national team level, there is too little training.

True. Fans are the worst judges there are. That being said, judging a national team coach is quite difficult because the number of games is limited, unlike a club where they can see the progress every week or every transfer window. A national team needs to produce results befitting their image in most competitions. Then again, that's the job of a functioning sports association. The bad news is we don't even know if the guys running the association are competent or not, most of the time (at least in my country).