Zidane and Pep Guardiola have their own uniqueness, even though Zidane was able to win 3 Champions League trophies but he only got it with one team namely Real Madrid, unlike Pep Guardiola he was able to get it with two different teams namely Barcelona and Manchester City even though it took enough time long ago gave City its first Champions League title.
But Pep Guardiola is able to win domestic titles with three different teams at the moment compared to Zidane only winning with Real Madrid, Zidane is only a manager for one team for now and there is no chance for Zidane to return to being a coach in a different team. PGS rumor will sign Zidane have get Luis Henrique and looking Zidane back as manager next season seems not possible yet.
I think it is unfair to limit Zidane champions league 3 peat exploit to just "because he managed Real Madrid" Carlo Ancelotti, Mourinho and Benitez all managed Real Madrid and they never won the three peat. Pep with the best team in Barcelona too did not win the three peat. Zidane won the 3 peat champions league title due to his grit, tactics and proper usage of excellent players. Players like Isco, Ascensio balled for Real Madrid in that champions league 3 peat, today Ascensio is in PSG, and am not sure where Isco is anymore.
Pep is a good manager ofcourse; and Zidane, refusing to take a new job does not make him a bad coach.