Fixing mouse acceleration and speed sliders in Devuan

Install xserver-xorg-input-evdev

These files are trying to claim input devices:

/usr/share/X11/xorg.conf.d/10-evdev.conf
/usr/share/X11/xorg.conf.d/70-wacom.conf
/usr/share/X11/xorg.conf.d/40-libinput.conf
/usr/share/X11/xorg.conf.d/10-amdgpu.conf
/usr/share/X11/xorg.conf.d/10-quirks.conf
/usr/share/X11/xorg.conf.d/70-synaptics.conf

The last one to claim a device will actually win over any that claimed it before. To make evdev claim the mouse (which for me fixed the mouse acceleration) you need to either rename it to 75-evdev.conf (which will move it to the end of this list) or copy it in /etc/X11/xorg.conf.d/75-evdev.conf which allegedly is also taken into account along with the /usr/share/X11/xorg.conf.d/ directory. If the touchpad doesn't work after this, use 65 instead of 75.