||Paradis have infrastructure and technology to actually get into offensive
Paradis people do not have that imperialistic ambitions and with this mass murder Eren committed they do not feel to strike on potential enemy.
For generations they nurtured besieged stronghold mentality and current situation will only reinforce it
Any new Eldians who would they get from Titans would be practically foreigners for Paradis and not additional manpower, assimilating them to society (assuming they want that) would cause more problems than any short term benefits
Any potential offensive would rely on resources and infrastructure of potential target to not turn into failure quickly and these would be lacking because of devastation of world, and if targeted country have these or managed to rebuild it, they could easily repel Paradis forces
Surviving world even assuming they focus on kicking crap out of Marley remands would gang up on Paradis if they actually tried something. Even if best case scenario for Eldians, that they could actually invade some country and continent they could not take rest of world and attack in all directions and without doing it, successful invasion will just leave their island open to invasion from other sides ||