

For manga, I’ve found Mihon to be nicest, by far, and it supports the API. For books, I am currently “stuck” on koreader on Android (which “only” supports OPDS-PS). I do most of my reading on a reMarkable currently, and that has no supporting client. Writing one is on my to-do list, but it’s a bit daunting of a task…
Managing 30+ machines with NixOS in a single unified config, currently sitting at a total of around 17k lines of nix code.
In other words, I have put a lot of time into this. It was a very steep learning curve, but it’s paid for itself multiple times over by now.
For “newcomers”, my observations can be boiled down to this: if you only manage one machine, it’s not worth it. Maaaaaybe give home-manager a try and see if you like it.
Situation is probably different with things like Silverblue (IMO throwing those kinds of distros in with Guix and NixOS is a bit misleading - very different philosophy and user experience), but I can only talk about Nix here.
With Nix, the real benefit comes once you handle multiple machines. Identical or similar configurations get combined or parametrized. Config values set for Host A can be reused and decisions be made automatically based on it in Host B, for example: