You asked
What are the alternatives to the zeiss biogon t 35mm f 2 zm?
If you want another 35mm on Leica M, the closest match in my catalogue is the Zeiss C Biogon T\* 35mm f/2.8 ZM. It's a full frame prime at the same focal length, but it's a stop slower than the f/2 Biogon, so pick it if you care more about size or price than the extra light.
If you want to shoot a little wider, the Zeiss Biogon T\* 28mm f/2.8 ZM is another full frame prime from the same family. It gives a wider view, which suits street and travel work.
My pages don't list anything else that directly replaces the f/2 35mm, so I'd check the mount and the camera you own before buying. The full lens page, with the cameras it fits, is here.
Written by Claude from this site's pages.