Honestly, if you're heading to the Swiss Alps, you want the Canon RF 24-105mm f/4L IS USM. I have been using this setup for a while and I am incredibly satisfied with the results. The extra reach at the long end is massive when you are trying to frame those distant peaks without trekking another three miles. Here is how I see the trade-off based on my time with the R5 series:

• Weight: The f/4 version is roughly 700g, while the Canon RF 24-70mm f/2.8L IS USM is nearly 900g. That 200g doesnt sound like much until you have been hiking for six hours through mountain trails.
• Low light: The IBIS on the R5 Mark II is insane. It gives you up to 8.5 stops of stabilization in the center. I've taken handheld shots at half a second with the f/4 and they look tack sharp. You dont really need the f/2.8 for street stuff anymore unless youre chasing super thin depth of field or absolutely need that 1-stop advantage for freezing moving subjects.
• Versatility: Having that 105mm reach lets you compress the landscape in ways the 70mm just cant touch. Plus the 0.24x magnification on the f/4 is actually pretty decent for flowers or mountain detail shots. The 2.8 is basically the gold standard for weddings, but for a one-lens-only travel kit, the f/4 works well and honestly makes the whole experience more fun because you arent constantly thinking about your heavy gear. I have no complaints about the edge-to-edge sharpness either... it is basically prime-level quality across the zoom range. Go for the 24-105 and spend the saved weight and money on some good hiking boots or some fancy Swiss chocolate!