Android users get the short end of the writing-app stick. iOS gets all the pretty indie apps. For SOP work, pretty does not matter. Reliability does. Here is what actually works.
Google Docs is the start and, honestly, the end for most people. The Android app handles long documents well, offline mode works, and sharing a draft link with a reviewer takes seconds. If your SOP lives anywhere, let it live here.
For catching ideas, Notion's Android app is solid. Keep a database of target universities, one page each: faculty names, lab pages, draft snippets. When it is time to customize each SOP, everything sits in one place. This is the mobile app for drafting SOP on the go use case done right.
Grammarly's Android keyboard is the unsung hero. It proofreads everything you type, in every app. Your 1am draft paragraphs get the same safety net as your emails. Pair it with a pass through an SOP grammar and structure checker tool, or a statement of purpose checker app free tier, before you finalize anything.
Dedicated SOP editor apps on Android? The category is thin, and I will be honest about it. Most are template wrappers with aggressive upsells. Judge any SOP editor app on iOS or Android by three questions. Does it export clean text? Does it work offline? Does it try to write the essay for you? Yes to the last one means walk away.
My take: Docs plus Notion plus Grammarly covers ninety percent of the job on Android. The last ten percent is human judgment. And for the final school-specific polish, the tailoring packs at sopexpert.fyi are worth a look.