Trying to unpack init_boot.img with kernel in it and I get kernel_size: 0 and etc. I can't extract kernel and ramdisk to edit them too

I receive these things, look at them down. I can't extract kernel and ramdisk to edit them too:
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_boot.img
boot magic: ANDROID!
kernel_size: 0
ramdisk size: 2073689
os version: None
os patch level: None
boot image header version: 4
command line args:
boot.img signature size: 0