I wouldn't call it a paradigm shift in terms of the code itself. The main thing is that it's a completely different set of system APIs that have to be targeted

I wouldn't call it a paradigm shift in terms of the code itself. The main thing is that it's a completely different set of system APIs that have to be targeted (by you or by the libraries you use). That means a lot of changes wherever those are involved, but they should mostly be straightforward changes (of course YMMV if you're having to use a new library/framework instead of just the new system APIs)