Thumb reader instead of pin

can i introduce login to sambapos with thumb reader (finger ) instead of PIN or password ? because of over the shoulder password stealing among waiters

There are many other options… MSR and RFID to mention a couple.
Both of these devices typically act as a keyboard to computer and samba knows no difference. The cards or fobs are just a number which is used for pin instead and a swipe or tap enter the pin number without touching the pin pad on screen.
Fingerprint readers have been asked about before however they are typically powered by software to decode the print to a user and given different software etc it’s hard for anyone to work with without having exact device. There is less standard comparability vs msr or rfid which are simple HID devices and even Windows doesn’t really see a difference vs any other keyboard type device.

I use rfid on all my tills. USB rfid readers can be purchased cheaply for arround £5 each and fobs can be bought in many qty for pennies.