Is 320px wide designs still relevant? (responsive web)

For a couple of years the smallest design I make for responsive websites is 375px wide. Now our new frontend developer eats my brain that I should provide 320px wide. And even if I will not she will scale to this minimum anyway. Smallest breakpoint is 480px. But the message is - good old 320px must be covered and scaling 375->320 is annoying (can't argue with latest thou).

I tried to ask Google, and got an article "Why your mobile site should still stay 320px wide" dated 2012... Should we, still, in 2019?

Need reasoned opinions.

Current project TA in short - a payable developer (more rarely - a scientist) located in a Western country. It's an API service, what increases probability of browsing from desktop - you won't manage and download api keys or copy paste code from documentation on a phone.