When I made an app I went and bought the cheapest Android I could find to check the thing ran ok as I use an iPhone normally. It was quite interesting - I made it display a bit less stuff and the UI less fiddly as the screen response was bad. I think devs should in general try catering for the worst devices and network connections. One reason WhatsApp won, especially in India, was it worked as a java applet on old phones when the competition couldn't be bothered with that.

I'm not convinced by the current trend of everything requiring a ton of javascript frameworks to display some text info and similar. It causes issues along those lines.