You can already do that without being a trusted device.
Do you think this changed in over 18 months? I think it changed in under 18 months.
If I’m not fully mistaken, I checked for the combination of iPhone as main device/Android tablet as iPad-like second device sometime in the past six months, at most since the beginning of the year, and it wasn’t possible (unlike phone + iPad as tablet, which seemed quite strange to me).
In any case, it’s a recently released change.