Frenkie is more vertical (down to his athleticism). Pedri and Gavi are more mobile in smaller spaces and hence better at pressing. It's a matter of style and pragmatism.
Not touching the Busquets topic.
No they are not even close to being better pressers of the ball and teams cut through the side far too easily when FDJ is out for one of the three.
They are not more mobile either. FDJ will get to ball and read it quicker in close stuations than those other two and can sustain it longer in games which in part his due to his age.
If Xavi was picking them with that belief it is worse than thought.
Gavi will go flying in when doesnt need to often and can result in crunching tackles or him being dribbled past or ball passed him too often. He has enthusiasm in bounds but it does make for great pressing and team is harder to go through middle of park against when FDJ there.