Android dominates the mobile OS market share though. Seems like targeting it would yield a higher ROI. Much like how malware writers target Windows, because it dominates the desktop OS market share.
Hope the HN crowd doesn’t take this the wrong way but, an Apple user tends to be a more valuable target. Think government brass, corporate elites and all their soft bellies, ie daddy’s teenage daughter or run of the mill mistress.
Android is fragmented (though that is changing slowly), which means it's much harder to port and validate a single exploit chain to work on many Android phones.
OP asked specifically asked for Google Pixel 4a. If the market being fragmented is working in your favor, why not use it?