You can add custom functions to Excel (e.g., the ribbon) and other Office apps using Visual Studio Tools for Office (VSTO). There’s almost nothing you can’t do once you have C# or other .NET languages in the mix (I like to use F#).

One of my collaborators (Ben Zorn) is one of the people featured in the linked article. We’ve been working on visual debuggers (and other things) for non programmers in Excel for a few years now.

There are many little things that just aren't available in Python-Excel libraries, that are available in VSTO.

There are also odd little things that Python database libraries don't implement, like SqlClient.SqlBulkCopy. Native bulk inserting is generally unsupported on Python, so I either have to spit out a CSV and use bcp.exe to bulk insert, or I have to use TurbODBC, a Python library (which has certain limitations, like not supporting certain datatypes like VARCHAR(MAX) or GUIDs).