I do see people online talking about using Excel to do knitting patterns.

I don’t know if his grandma just “accidentally opened it”—maybe she heard about it from someone else—but it does look like it’s a thing.

I’d probably suggest using a pixel art app or something instead, but, well, Microsoft Office is pretty much everywhere.

Reddit, 5 months ago:

https://www.reddit.com/r/knitting/comments/1rz5udj/creating_patterns_on_excel/

Knitting website, 15 years ago:

https://anniebeeknits.wordpress.com/2011/06/06/charting-in-excel/

Charting knitting patterns in Excel

I do all my charting in Excel, personally. Mostly this is sheer laziness, since it’s the software I know best from my day job, and I can’t be bothered to purchase or learn another program! Anyway, I had some tips and tricks to share with Glenna, and I promised I’d make her a proper tutorial. I’m hardly an expert (at Excel OR at designing) but maybe this will prompt some others to share their tips and tricks too. Here goes!

Knitting website, 16 years back:

https://www.chemknits.com/2010/01/how-to-make-knitting-chart-in-excel_9394.html?m=1

How to Make a Knitting Chart in Excel (Part 1 - Setting up the Chart)

A comment on my peptide beer cozy pattern page inquired how I was able to make the chart look so good. You can go to an office supply store and purchase graph paper. You can download graph paper online. But how can you easily make a chart of your own design and share it on the web? In this article, I will give you a tutorial for using Microsoft Excel to generate your knitting charts. In Part 2, I will discuss how to draw your chart and in Part 3, how to save and share your chart.

It looks like people have developed a set of conventions using Excel functionality to colorize cells based on the characters in them, so they can rapidly input patterns using the keyboard.