Can the developers consider in a next release an easily customizable greeter? I mean, what if I want to easily retheme the login without much fuss?
Maybe if you ask the developers directly (SDDM) and if you explain, what “easily customizable” means.
There are a few threads regarding this issue already in the Discourse. You might want to check them out. Search for SDDM. I believe @wxl said there is a GUI customizer in the works but it isn’t ready yet.
@Chris that’s true but even that doesn’t deal with theming.
tl;dr @volomike no. Linux distributions, by and large, are simply collections of already existing software. Developers of these distributions work hard on things like integration and will often send small patches upstream, but the development of the software itself is done by the upstream developers. So @apt-ghetto is right: this is a question for SDDM.