How do I Migrate from 4.3.x to 4.4.x?

Migrating from 3.x to 4.x required me to practically rewrite most of the code in my project because it was almost like changing languages. It seems this may be is the case for moving to 4.4.x from 4.3.x. I have looked at https://codeigniter.com/user_guide/insta...e_440.html but I cant understand much.
I looked at the https://www.codeigniter.com/user_guide/t...pages.html and found that
$routes->get('pages', 'Pages::index');
now becomes
$routes->get('pages', [Pages::class, 'index']);
and realised that controllers no longer use 'echo' to spew views. Instead they use 'return'.
Is it possible to get a list of all the things that must be changed for migration?