Seen and done all those. I've guided over the past 30 years and all sorts of things can happen.
Bipod. Really this only works in situations where you can lay prone and vegetation is relatively low. Very valuable tool in the right country.
Sticks. Work well for higher veg and shooters who struggle to get into prone awkward positions on the mountain side. Good sticks with a practiced rear support is very stabile.
Tripod. Light weight tripods designed right, fiesol 3342 for example, can do it all. Best option but they do weigh more than a bipod or sticks but you can leave both home. Just not as fast to deploy. So, you need to practice.
Buddy system and back pack. Yep, can and does work with practice and a partner who knows what to do. The issue is mainly that if you partner isn't spotting for you because they are being used as a barricade is kind of bad. Buddy is my last resort but it works. Killed elk and deer this way, just not preferred.