I am using Debian 11 with KDE, i am trying to replace the deb packages for KDE applications with equivalent snap packages from https://snapcraft.io/.
However while i found some of them others are either outdated or missing completely, is there an alternative install source for the remaining packages?

Why? It makes no sense not to use the packages provided by your distribution.

FWIW: we don't make packages, that is something distributions do