I agree that the lack of a microSD slot is annoying, though not entirely unreasonable with the whole value proposition of a "ruggedized" phone.

The FM radio is entirely baked-in to the MediaTek MT6789 SoC, and uses anything connected to the 3.5mm jack as the antenna for better reception. Assuming this thing is intended for use at jobsites, it's not entirely unreasonable to assume that having a functional FM radio and 3.5mm jack would be desired.