If your Android phone is low-end or mid-range, Microsoft wants you to have the best emailing experience, no matter what. As listed on the Microsoft 365 Roadmap, Microsoft is working on a new Outlook Lite app for Android.
First added to the roadmap back on June 30, Microsoft is aiming to roll out this new Outlook Lite app in July 2022, which we've just entered. There are not a lot of details on how it'll visually differ from regular Outlook on Android. However, Microsoft mentions that this is an Android app that will bring the main benefits of Outlook, but in a smaller app size with fast performance for low-end devices on any network.
Such an app would be perfect for Android Go phones, which typically have low-end specs (though this hasn't been confirmed.) Either way, as Paul Thurrott points out, there are other versions of "lite" Android apps. Some examples include Facebook Lite, Instagram Lite, and Google Go.