1. It's just an archive

bsdtar -xf "package_0.1.0-1_amd64.deb" data.tar.xz
tar xf data.tar.xz

this will give usr directory containing binary in usr/bin/ and other data in usr/share

❯ tree usr
usr
├── bin
│   └── somebinary
└── share
    ├── applications
    │   └── io.github.some.package.desktop
    ├── doc
    │   └── package
    │       └── copyright
    └── icons
        └── hicolor
            └── scalable
                └── apps
                    └── io.github.some.package.svg

10 directories, 4 files

2. One liner:

bsdtar -O -xf "package.1.0-1_amd64.deb" data.tar.xz | bsdtar -xf -