The device displays cellular issue

My iPhone has a cellular issue where the IMEI is visible, but the Modem Firmware is completely blank

-My battery health is currently in the 70s, and I am unable to proceed with any iOS updates, even though I have plenty of storage space left on the device.

-I’ve already tried basic troubleshooting like resetting the network settings. I heard that attempting a full factory reset (DFU restore) while the baseband is dead will brick the device (activation error), so I haven't tried that yet

Wi-Fi and all other features are working perfectly fine without any issues. In this case, is a logic board baseband/modem repair the only solution? If I get it repaired, how much longer can I realistically use this phone?