I wrote a fuzzer "dumb fuzzer" and used a sample from http://www.ccp14.ac.uk/ccp/web-mirrors/bca-spreadsheets/scanplot101.xls  which I randomly found on the internet. I mutated the data and tested roughly 1000 cases on several Document Reader Applications for iPhone.

https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/13825.xls (goodreader_poc.xls)