[Treadmill] What's the best thing I could do to prepare for hiking

So I've always wanted to hike but my endurance is super bad so I joined a gym to train my endurance on a treadmill while weightlifting a bit to gain strength. Till now I've been progressing with high low blocks (HIIT) and it's been going very well and im seeing progress everyday. However I was wondering what would be better. High low blocks to train endurance even more (walk-runs) or long walks with incline % variating? I'm really lost rn 😭😭