no service

Did you put your new SIM in the device or register your new eSIM?  Have you removed your previous Verizon SIM or eSIM from the device?  Have you checked to make sure your APN Settings are correct?  T-Mobile devices use Google's stock implementation of VoLTE to make and receive calls.

https://www.t-mobile.com/support/devices/not-sold-by-t-mobile/byod-t-mobile-data-and-apn-settings#:~:text=In%20Settings%2C%20look%20under%20Wireless%20%26%20Networks%20or,update%20the%20following%20settings%20for%20the%20Data%20APN.