I have a Voitlander Nokton 40mm, the Voitlander are very good, imo. Cosina are a manufacturing partner of Carl Zeiss so would be able to make good stuff.
You can get great lens almost as good as Leica for a fraction of the cost (like Konica Hexanon).
I’m wishing for a full frame non-leica m-mount RF. It seems logical that someone should make one, especially now that the first mirrorless slr-type camera has come out.