[data grid] Use row spanning with Excel export

[TarasRospodniuk]

The problem in depth

I need to investigate the possibility of exporting data in Excel format with row spanning support. I couldn't find any working examples in the documentation. When I try to export data in Excel format with the unstable_rowSpanning prop set to true, the generated file does not include any row spanning.

How it looks in Datagrid:

And in Excell:

Your environment

`npx @mui/envinfo`

 System:
    OS: macOS 15.3.2
  Binaries:
    Node: 22.11.0 - ~/.nvm/versions/node/v22.11.0/bin/node
    npm: 10.9.0 - ~/.nvm/versions/node/v22.11.0/bin/npm
    pnpm: Not Found
  Browsers:
    Chrome: 135.0.7049.85
    Edge: Not Found
    Safari: 18.3.1
  npmPackages:
    @emotion/react: ^11.11.1 => 11.14.0 
    @emotion/styled: ^11.11.1 => 11.14.0 
    @mui/base:  5.0.0-dev.20240529-082515-213b5e33ab 
    @mui/core-downloads-tracker:  5.17.1 
    @mui/icons-material: 5.16.6 => 5.16.6 
    @mui/material: 5.16.6 => 5.16.6 
    @mui/private-theming:  5.17.1 
    @mui/styled-engine:  5.16.14 
    @mui/styles: 5.16.6 => 5.16.6 
    @mui/system:  5.17.1 
    @mui/types:  7.2.24 
    @mui/utils:  5.17.1 
    @mui/x-charts: ^7.7.0 => 7.28.0 
    @mui/x-charts-vendor:  7.20.0 
    @mui/x-data-grid:  7.22.2 
    @mui/x-data-grid-premium: 7.22.2 => 7.22.2 
    @mui/x-data-grid-pro:  7.22.2 
    @mui/x-date-pickers:  6.20.2 
    @mui/x-date-pickers-pro: ^6.18.4 => 6.20.2 
    @mui/x-internals:  7.28.0 
    @mui/x-license: ^7.12.0 => 7.28.0 
    @mui/x-license-pro:  6.10.2 
    @types/react: ^18.3.17 => 18.3.18 
    react: ^18.3.1 => 18.3.1 
    react-dom: ^18.3.1 => 18.3.1 
    typescript: ^5.3.3 => 5.8.2 

Search keywords: row spanning, excell, export

Order ID: 95688

[arminmeh]

Hey @TarasRospodniuk
At the moment this is not supported, but it could be a useful feature.

I will add this to the board for the team to look at and prioritize.