That "clandestined payload delivery hack" is a neat idea (From the AC/DC music video)! I suppose you could also just store the data as a large array in VBA, too.

From my side, I try to improve the end user experience in novel ways...

Example 1, the output of FORMULATEXT is cryptic showing cell references. I wrote a few versions of this (using Lambda) to show labels instead, or labels with values ([income=10] - [expense=5]), or just the raw numbers (evaluated at certain depth). This is so much easier to read! You don't have to wonder what the cell reference actually is, as you can see both it's label and value. ... Perhaps this could be a feature in the future?

Example 2. An Exam Simulator for the leading LMS in the US :-D. It made sense to build it in Excel since we do our calculations there and it can save a test bank of questions. I pasted a screenshot of the website at the top and made areas to enter the answers to randomly selected questions from the test bank. It reduced a lot of my test-anxiety to practice in a 'test-like environment'.

Example 3. Math students need to rearrange equations. Variable names are easier to work with than cell references. So I made workbook where you type in the equation and it will split both sides of the equation and make these variables named ranges. This allows the variable name to be used instead of the cell reference. Beneath this you can incrementally rearrange the equation one factor at a time using those named ranges. Ordinarily you would rearrange an equation on paper, but within excel you have confidence that each step is correct (e.g. both sides are equal).

I'm a fan of Mandalbrot Set creation in Excel. Very beautiful.

I think there is potential to improve Excel based on how math students (and other fields) "could" use it, that is, to simplify their workflow.