I see.  Are the pads castellated and manufactured by any of the regular Chinese cheap pcb fabs?   Is so, how do you specify the castellation in the layout software?

no china fab, no :) EU fab, has "cut hole" as standard offering. They do not like to do this, but they do.

But taiwan fabs make this also, no questions asked, even with V-scoring :) ok with 100mil and 1.0mm PCB was V-scored holes pretty ok!

With that many pads it could be a breakout board for the chip itself. ^_^   I guess that just a few of them are actually connected to something?

This mod was part of SMD64 series that all share same footprint and loosely agree on placement on digital and analog in outs. For this module many pads are no connect.