Actually after having done more reading it looks like armeabi-v7a covers most of arm64-v8a, so I got the above APK down from 37Mb to just 20Mb.
This is a great way to reduce APK size to a minimum with relatively little impact, especially if you’re targeting specific users - for example if you’re creating apps for internal business use and using a managed play store.
(But, if you’re doing a general release, or want to target tablet devices, perhaps don’t remove the other libraries…)