Similar questions (like this one) are, unfortunately, too much outdated
I have a Razer Mamba Tournament Edition and its minim speed, set via the OS settings, is still too fast
Playing with xinput-gui
I found my mouse being id=12
elect@5800x:~$ xinput --list
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ Razer Razer Mamba Tournament Edition Keyboard id=8 [slave pointer (2)]
⎜ ↳ Razer Razer Mamba Tournament Edition id=12 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Power Button id=7 [slave keyboard (3)]
↳ LEOPOLD LEO 98Keyboard id=11 [slave keyboard (3)]
↳ Razer Razer Mamba Tournament Edition Keyboard id=9 [slave keyboard (3)]
↳ Razer Razer Mamba Tournament Edition id=10 [slave keyboard (3)]
and the field I want to modify being libinput Accel Speed

but setting anything below -1
returns an error
subprocess.CalledProcessError: Command 'xinput set-prop 12 579 -1.300000' returned non-zero exit status 1.
Greater values work fine
xinput set-prop 12 579 -0.100000
but they are not useful for me
I'm on Ubuntu 22.10