I've been using Second Copy for over fifteen years - which backs up all folders and files I choose - to an external drive.
Complete C-drive backup is done via the Lenovo software that came embedded in the computer (Lenovo Rescue System 4.0). It works pretty much like a Windows image backup.
A third backup copy/drives is kept off-site.
I could put some hardware in a container and bury it in the ground near the house. It would have the performance and security of on-site, and the fire resistance of off-site. And it would be super cheap. I think it’s a very interesting idea.