$ sudo tee /etc/apt/sources.list.d/debusine.sources <<END
Types: deb
URIs: https://deb.debusine.freexian.com/freexian/debusine
Suites: trixie-devel
Components: main
Signed-By:
  -----BEGIN PGP PUBLIC KEY BLOCK-----
  .
  mDMEaaX1bBYJKwYBBAHaRw8BAQdAfpkAx9/TxpbnGHezlUiruo7YT0EcFHEQ9Swt
  65r8wEa0KUFyY2hpdmUgc2lnbmluZyBrZXkgZm9yIGZyZWV4aWFuL2RlYnVzaW5l
  iJAEExYKADgWIQT8mEBDdxrXXLXVVA1rNLmlWenTHAUCaaX1bAIbAwULCQgHAgYV
  CgkICwIEFgIDAQIeAQIXgAAKCRBrNLmlWenTHDBIAP0S1OwE1zTfV+0jFXYZW6J8
  dcS+fKF1S1YCi6cXLuWzZwEApcVXixlRDzOmQQBymyG35nf2ZRYFuhLOlkD/Ad/W
  Xg8=
  =VWZC
  -----END PGP PUBLIC KEY BLOCK-----
END
$ sudo apt update