alt Hacker NewsMy back-of-my-head benchmark is still my old Amiga. Here's[0] a full-blown GUI email app that was perfectly nice to use. The entire package, complete with all its custom GUI classes and 3 sets of icons, took 1.4MB uncompressed.
I know the thousand legitimate reasons why modern apps are larger. It's not all bloat and inefficiency, either, except in the harshest sense that old apps tended to use byte-optimized data structures like linked lists instead of faster, but less space-efficient structures like hash maps. They have to deal with higher resolutions, although the command to draw an empty white 320x200 square on the screen should be approximately the same size as to draw a 2000x1500 one. And yet, wow, it doesn't seem like it should need to be that much bigger.
Thunderbird for Android supports pretty much everything Gmail supports and probably more, but it's "only" 40MiB in size. Even on Android, that's a 3x size reduction.
I don't know why iOS apps in general are so much larger than Android apps (that doesn't just seem to be a Google problem) but you certainly don't need the full size of the Gmail app.