plasma-manager VS kde-configuration-files

Unfortunately until we find more volunteers in this area, it is hard to see status quo changing. See also https://github.com/nix-community/home-manager/issues/607 and this ongoing project https://github.com/pjones/plasma-manager

Plasma-manager solves both backup and sharing.

A dude wrote a tool to configure KDE with Nix. https://github.com/pjones/plasma-manager Sadly it's a bit iffy, and settings aren't applied until you relog and other things.

Normally yes with the help of home-manager, but you cannot manage your Plasma configuration declaratively, yet. I think there is an effort for configuring Plasma here, but it is not complete yet and did not get any updates since September so maybe it is abandoned or paused for now? If you are fine with using Gnome, there is a dconf module in home-manager so you can also make your desktop environment reproducible. There is also xfconf module for configuring XFCE if you prefer that but I did not use it so I don't know if it is as good as dconf.

however, there is the Plasma Manager which should give you similar or even the same experience as GNOME

Although I still have to look into plasma-manager

As for declarative usage for KDE or Firefox, while I haven't done it personally yet, it is possible by adding extra modules. Home-Manager has config options for Firefox and Plasma Manager, an home-manager module for KDE.

Think I'm going to start using plasma manager and maybe try to contribute.

I've been using plasma manager for kde, it has a command to dump the current configuration to a nix file which is convenient https://github.com/pjones/plasma-manager

On NixOS (probably irrelevant for you, but may as well mention it for others) I've been using plasma-manager.

Currently mainly through copying the configuration files, which are in a big heap under ~/.config (a list is at https://github.com/shalva97/kde-configuration-files)

You may want to take a look at the following repository: https://github.com/shalva97/kde-configuration-files

https://github.com/shalva97/kde-configuration-files in this repository are noted many config files for different KDE related stuff. and also some handful of commands that might help you to automatize workflow. Examples like using kwriteconfig5 for different files.

No idea.. I never tried to reset plasma settings. Try to google that. This may help you tho -> https://github.com/shalva97/kde-configuration-files

Overview of KDE configuration files: https://github.com/shalva97/kde-configuration-files

The Arch wiki on KDE points to a GitHub repo someone made, don't think there's any similar official version though.