This reminds me a lot of calculators I use for FIRE, ie the ones shown here [0]. Perhaps I should try Causal for personal use as well as for business use. I've also seen Maybe [1] for personal finances, which looks good too.
It is likely that I won't do that in the case of your program, just letting you know as I just use my own Excel or Google Sheets program. If you would like to include it, please feel free to do so.
[0] https://engaging-data.com/early-retirement-calculators-and-t...
[1] https://github.com/maybe-finance/maybe