Some of the issues have turned out to be unrelated to each other. I think the page animation issue is related to the MVVM framework I'm using.

However, the answer to the question of what is slower between Xamarin and MAUI, in this case, is SecureStorage.

This is a github issue (https://github.com/dotnet/maui/issues/18817) regarding SecureStorage calls that don't resolve in the App constructor (which has nothing to do with my issues as far as I know). Further down the discussion there are some posts that mention the poor performance of SecureStorage.GetAsync. So far, I've seen marked improvements in areas where (admittedly because of laziness) a GetAsync call was on a hot path. This issue also seems to explain why the MAUI performance in the emulator was similar to Xamarin, as opposed to on the physical device, in addition to only affecting Android.