Kante judging by his actions is a great and humble guy and in Saudi Arabia he will be comfortable, but Benzema is still a star of another level, the attention to him will be more and it will probably be harder for him to adapt than Kante.
I would not say that Kante is a tough player. He is not afraid to go into clashes with the opponents and as a great midfielder-supporting did a great job, it was almost impossible to go through Kante, but it seems in his career he has never seriously injured anyone, did not break his legs. He's a tough midfielder, but not violent and didn't intentionally break other players out of emotion or anger. And I think other players respected him for these qualities, feared him as a competitor, because Kante always gave his all on the field, but always within the rules.
It is even nice that such a player can earn good money now and please the fans with his game for another couple of years.
We must also admit that the quality of the Saudi league will probably grow a lot with the star players who have joined recently.
I think Benzema would adjust a lot better, Kante will adjust a lot harder because of exact the reasons you gave. Kante is a humble guy, in Saudi Arabian league he is a superstar. Which means that if we are talking about having an insane amount of attention to him due to being a superstar, he will not be happy about it, even at Chelsea when he got a lot of attention that just meant he wanted to stay out of flashlights and that's why it was a trouble for him.
At premier league there are many bigger stars than Kante so he was capable of doing it, here in SA he will be one of the biggest ever names in history of the league, probably behind only Ronaldo and Benzema. Benzema on the other hand is used to be being a star, and he will be star there too, so he will adjust easier.
Well now the Saudi league has invited a huge number of top players. In addition to the already signed Kante and Benzema there is also Ruben Neves, who is only 26 and has not yet reached his peak, today Chelsea should sell a good and stable goalkeeper Edouard Mendy. Perhaps still be able to sign Hakim Ziyesh, the more so he is also a Muslim and in principle should also fit normally in the Saudi league, and given the fact that Ziyesh is still young enough, he is only 30 years old, perhaps the peak of his athletic career is still ahead. He is a versatile player and can reinforce any team, just a bit lazy, unlike Kante. But the Saudi Arabian championship is not as fast and intense as the English Premier League, so even if he doesn't play to his full potential, Ziyesh shouldn't get lost on the field like he did at Chelsea.
There are also talks with one of the best holding midfielders in the world, Sergio Busquets.
So not now against the background of other players Kante will no longer look like a super star, but just a top player.