To be honest this is really a very specialized area that there are very very few people in the community really know about it. Your going to have to dig into the runtimes and understand how they work and you will also want to know how to build the runtimes from scratch as implementing codepush will probably require some actual runtime changes.
I ended up having to do a complete rewrite to even make my NativeScript-Updater work on iOS, I had it working on Android well over a year ago… So this isn’t a simple project and it took me over a year to get to the point of releasing it (hopefully I can get it actually packed up and out this week). I am considering changing my plugin to use CodePush in v2.0; but it really depends on how much paid support there is in v1.00 for it to justify doing the additional coding that would be required.
But unless someone paid me for those efforts, it would still remain a commercial plugin.