I converted to an 8" system but now voice commands, navigation prompts, and phone calls isn't working

This is an issue with your conversion harness (or lack thereof). The issue is that the connection between the APIM and the ACM for these features isn't there.

ACM harness pins 8 and 21 respectively go the APIM harness pins 3 and 4. This does the bluetooth voice for phone calls, voice commands and navigation instructions. Without those wires connected, that audio won't exist.