Even if it were possible, I wouldn't recommend connecting 100 devices to a generic account from both a security perspective, but also from a visibility perspective. You wouldn't see what users are doing in the app.
I would possibly look at enforcing the time clock so that users have to clock in and out of shifts. If there is no data for clocking in and out then you can identify the users and take remedial action
The other recommendation is to potentially look at them using their own phone with the Teams app which you could look to enforce app permissions policies in Intune. Intune allows Mobile app management without MDM and enrolling the phone