Creating a Teams phone using a Wi-Fi only Android or iOS phone in kiosk mode.

I do not have experience with Teams specific. But I have some experience with Android kiosk.
You have the option to use single of multi app kiosk.
I would recommend to use a multi-app kiosk, because the single app currently has a bug that allows you to exit the kiosk.

Here is a good guide: https://www.robinhobo.com/how-to-configure-an-android-device-in-multi-app-kiosk-mode-with-microsoft-intune/