Oppo Phone cannot install Google App - only Google Go pre-installed allowed

[AJTex]

Good day

I have a Oppo phone with Google Go pre-installed.  I purchased a Google Nest Mini and followed all instructions until I got to the part where I was asked to install Google Full App.  However my phone does not allow me to install the full Google App and I cannot uninstall the Google Go app.
Now I'm stuck, as Google Home requires the Google full version and now I cannot continue with my Google Nest Mini setup.

Did I purchase my Google Nest Mini for nothing?

Please any help / assistance will be much appreciated.