Manufacture a Cheap 4" screen smart phone able to be carried in one's pocket
Yes, I am an old dinosaur! I have carried a flip phone (basic) in my shorts/trouser pocket during my waking hours for many years and I don't have it glued to my ear. It is carried for emergency & convenience & not many calls/texts are made from it but I do receive calls, texts/messages.
I would like to have a 'smart' phone so as to use the Covid check-in app + Debit Card, Dr/lic and a few other apps. There are several modern and affordable (under or arount the AU $200 mark) Android mobiles with good battery capacity available but most feature around 6 to 7" screens and thus the phone is large and has to be carried in hand and not suitable for pocketing.
Phones such as the Apple 4 or SE are of a pocketable size but are expensive and dated. I am sure that if a modern smart phone around the 4 or 4+ inch screen and modest body size could be produced, it would be a good seller.
In recent times I have met so many people asking for such a mobile of pocketable size and so justified my requirement.
There are a few 2" to 3" screen mini smart phones available on the internet. Great to carry in one's pocket but reviews do not credit them for quality or reliabilty and the screens are perhaps too small.
Have you tried
https://www.catch.com.au/deals/android-flip-phone-australia/
Opel Mobile SmartFlip (4G/LTE, Keypad) - $129but it does say it cannot read QR Codes and does not work with Covid Safe apps
there are others there, pending on your individual circumstances
You can set your price limit and your particular needs
you could also check out Coles, Woolies, Big W and Post Office Catalogues
and let me know if you find anything exciting and I just might follow your lead :)