I’ve been running EndeavourOS (Arch-based with really good defaults and a very helpful community) as my daily driver for two years, and honestly I feel the “Arch isn’t stable” trope to be way overblown, based on my experience. I personally had more issues with Fedora and OpenSUSE Tumbleweed than I have with EndeavourOS so far.
Also, if Wayland is a priority then I would suggest sticking with Gnome. KDE has come a long with their Wayland support but it’s still pretty buggy in comparison.
P. S. If you do fancy trying the KDE route anyway, I would disagree with the other commenter and say that Debian is not an optimal distro for KDE. This is mainly due to the fact that KDE development greatly benefits from quick updates via a rolling distro, and Debian is pretty much the antithesis of that.