As some others have said, there’s no alternative to hiking with a heavy pack. Even if proximity to the mountains is a challenge, walking around the neighborhood at a good clip with a progressively heavier pack for progressively further distances should be a part of any pre-season program.
That being said, I’ve done every program MTNTOUGH has designed and they all have a place. Hiking alone will leave you with deficits, whether it’s strength, mobility, or top end cardio. MTNTOUGH has done a great job providing well rounded programs to follow during different parts of the year. In the strength and conditioning world, this equals specificity and progressive overload. It’s always worth a shot, and you get what you put into it. Follow it for a full program and track the differences.