This can be done no matter what SMS/MMS app you use, but it is slow.
SMS Import / Export (Imports and exports SMS and MMS messages, call logs, and contacts.) https://f-droid.org/packages/com.github.tmo1.sms_ie/
This can be done no matter what SMS/MMS app you use, but it is slow.
SMS Import / Export (Imports and exports SMS and MMS messages, call logs, and contacts.) https://f-droid.org/packages/com.github.tmo1.sms_ie/