You’re right, I thought I remembered that article giving actual figures but instead it just handwavily says they didn’t sell many.

So, here is one that actually quotes a number, 3% of the whole iPhone lineup: https://www.macrumors.com/2022/04/21/iphone-13-mini-unpopular-march-quarter/

And another: https://www.cultofmac.com/news/iphone-13-mini-makes-up-a-tiny-percentage-of-apple-sales

And another, this one says 5% for some reason: https://www.notebookcheck.net/iPhone-13-Mini-sales-continue-to-disappoint-as-rumors-claim-the-iPhone-14-Mini-may-be-axed.593194.0.html

Either way 3% - 5% is a small number for Apple (or Samsung, or…) which might not justify making a small phone, but in absolute numbers, thats actually a lot of people! A smaller manufacturer should definitely be able to profitably fill this niche…