When I search for phones with 3GB+ RAM and <=140mm height, there's only iPhone SE, iPhone 12 mini, and iPhone 13 mini.
The fact that Apple released 3 phones in 3 years with this form factor shows me that it is a profitable market segment and that there is demand.
Why is there no Android equivalent?
https://m.gsmarena.com/results.php3?nYearMin=2019&nHeightMax...
https://www.productchart.com/smartphones/small_android_phone...
You can move the "RAM" slider to 3GB which will show the phones that have 3GB or more. And the screen slider to your desired size. A height of 140mm means the phone would have a display size of roughly 5 or 6 inches.
For the USA, it gives me 90 phones with 3GB and up to 6 inches.