As discussed in Plasma meetings and Akademy's, Oliver Beard and I have been working on incubating SDDM into Plasma whilst also providing a more coherent Plasma experience.
This has been implemented as two new repositories: https://invent.kde.org/davidedmundson/plasma-login-manager) a continuation of SDDM with full history. https://invent.kde.org/davidedmundson/plasma-login for front end and KCM code. It doesn't have to stay that way. The front end was separate because I tried using greetd first. Then the backend is separate as it has SDDM history imported. We can choose to merge them, or put the front end in plasma-workspace. I'm not sure what we want. It's not quite at a stage ready for official kdereview, but ready for development. I've written up a blog post, because social media will pick this up this thread anyway, and I wanted to explain some previous discussions without rehashing here: https://blog.davidedmundson.co.uk/blog/a-roadmap-for-a-modern-plasma-login-manager/ David