For migrating articles and categories you have several components that works. But if you want to import for example some components data then you will probably have to write php migration script to move data from one to another mysql table and make references.
It should be no pain, like going from Joomla 4.1 to 4.2, for example but in reality only small and simple web sites goes painlessly from 4 to 5. They again promised one-click-migration and again made a screw up.
It will be a miracle if all components which are at least fairly common gets upgraded to support J5 until 2025. For example, K2 still doesn't have version that works on J4.
Sooner or later we will all be forced to update on J5 from J4, so it's time to make strategies and check out list of compatible plugins... Until everything is compatible I'm not migrating.
Component is great, when it works. But under any circumstances, do not install it on live site, it tends to install a lot of it's own garbage that can not be uninstalled, without breaking whole website. Use it only on test version!