It is possible to install Devuan/Debian stable and then editing
/etc/apt/sources.list upgrade to a testing/unstable branch (ref).
However on my laptop I have an AMD Ryzen 7 2700U processor, which does not support Linux kernels before 4.10, so I just cannot install the stable versions (kernel 4.9) to start from.
Where can I download from and install the latest unstable versions (e.g. Devuan Ceres) directly?