The Extensible Firmware Interface is what most people are used to as it's what modern x86_64 systems use.
However what most people don't know is that you can use it to load linux directly!
An example script is available here. (Be sure to modify it)
U-Boot Documentation is actually great, No need to rephrase their docs.
I will add a build script here eventually..
Android devices tend to use a file called boot.img that usually contains a kernel and initramfs.
Some also contain device trees in there, In other cases device trees are stored in the DTBO partition.
To create an Android boot.img you can use mkbootimg and to extract existing ones you can use unpack_bootimg
Both executables are provided by the android-tools package.
An example script to boot linux on Android devices can be found here.