Avoiding re-inventing a wheel

I need to expand my client relation management/sales tracking application
from its existing python3/Qt5/SQLite3 version to a more capable one built on
a postgres backend. (For the record, I've been using postgres and sqlite on
linux for almost 20 years now so I'm comfortable with both.)

Before I end up re-inventing this wheel I'd like to learn if someone has
such a tool available and is willing to let me copy it for my inhouse use.
If not, I'd appreciate opinions on whether I should write the application in
python (with wxPython as the GUI) and use postgres as the backend or build
it primarily with postgres with python as the middleware and something for
the UI. All my previous science/business applications have been written in
python and pass embedded SQL to the postgres back end; I've not tried to use
all the postgres capabilities to make development quicker and easier.

Your thoughts?

Rich