What is the current approach to doing hot code reloading?

I’m trying to use hot code reloading in my app. The app in question is deployed using mix releases.

As I understand it, there was once a project called Distillery, but it is now dead - most of functionality was merged into mix release. Howerver, the hot code reloading support didn’t survive the migration - according to the docs Distillery was capable of generating appup files, but now I failed to find any tools that could do anything like that. Seems that the only remaining route is to write the appups myself.

Are there any known tools that simplify the task of writing appup files? Or does everyone write the appup files by hand?

P.S. By the way, I’ve read about and am aware of many issues and pitfalls that await unlucky souls that are going down the hot code reload path. But in my particular case, the application is maintaining a significant number of stateful connections, and it will be very nice if these connections can be preserved, if possible. And the upgrades aren’t expected to be very difficult - most of the processes are using GenServers, state is kept in maps, etc.
I understand that many suggest using blue/green deployments and docker and whatever, but I think that there’s some middle ground to be had - I can always go the blue/green road if some particular upgrade is difficult to do with hot reloading, but in most of simpler cases I can save lots of pain by simply loading the updated modules.
As someone said, “there’s a distinction between relying on hot deploys and simply enjoying them”.