I went through this exact same struggle before trekking the Alta Via 1. I eventually settled on the Canon RF 14-35mm f/4L IS USM and honestly, it works well for that terrain. People freak out about the distortion at 14mm, but it works fine once the profiles are applied.

• Handling: The 77mm filter thread is way more reliable for circular polarizers than the bulky setups needed for the 15-35.
• Software: The R5 Mark II sensor is smart enough to correct the raw files automatically.
• Fatigue: I learned the hard way at Seceda that every gram matters when you are climbing 1000 meters of elevation. I prefer staying safe with a lighter kit that actually makes it to the summit. The f/4 is sharp enough when stopped down for landscapes. It keeps you within budget too. You dont want to be lugging glass you wont use.