I think it is meant to be a generic phone, the edges and front camera are wrong for an iphone, but then the home button is very distinctly an iphone. It is weird.

it's either an iphone 4 or iphone 5 in a case. the home button is an iconic giveaway.

It is in fact the Facebook Phone!

Or at least a mockup of one.

It has the front-facing camera in the top right corner, which is a hint!

Googling suggests the Facebook phone was an HTC device?

I think that's a BlackBerry. The later Motion from 2017 had a singular button down there too. Could be an older version but can't find anything.

i don't think it's an iphone

Correct - it's not an iPhone.

It's the Facebook Phone!

(probably)

Could it be an iPod Touch?