As OP said, don't worry about the exact blend. As long as there is some propane in the blend.
Switzerland - a land of many tracks and many walkers. Very walker friendly, and shopping is fairly easy.
The (blue) French CampingGaz Twist-Clik canisters look similar to the screw-thread ones, and are usually readily available, even in small towns in the local General Store. They are however incompatible with the Giga stoves unless you manage to buy an adapter. You can buy French stoves which, while not as light as the Giga stoves, do work fine.
The French Bleuet puncture canister is also widely available, but I think they are a bit dangerous as they cannot be resealed and I have had one leak in my pack.
The screw-thread canister is often available in big gear shops in large centres, especially if they are selling other MSR gear. I don't think I saw many in small towns however.
I don't remember seeing the Coleman green LPG cylinder anywhere, but maybe in the big gear shops.
White gas can be very hard to find, although you could buy petrol from a garage. Ugh. Alcohol - variable.