Exactly: full fledged Word Processor, optimized for the contextual technology of a ~13'' EPD display (so, for example, no scrolling, corner-to-corner (but the margins) use of the display in two columns landscape - for use with a slotted BT keyboard). Native Java for Android (no need for NDK). Rich text and full paragraph justification, spacing and indenting - from scratch: text is rendered and placed on the bitmap of the screen canvas bit by bit whenever necessary upon editing. Functions through touchscreen and keyboard shortcuts. I structured a markup (using both paragraph styles and ad-hoc "direct formatting" - bold, italics etc.) which allows for simplicity and comfort in file manipulation, but the translation to .fodt (or .xml in general) is almost trivial (there are libraries around to manage typical formats: I have checked but not implemented as for personal use I do not really need the feature). Battery wise, I managed to remain very conservative: sometimes even 2%/hour (~100mA, equivalent to many days of work) of consumption (fortunately, also the use of BT keyboards consume very little).
It was started this June (2021), and I have used it for many hundred of hours with good productivity. I have not published it (yet) as I would want to polish the code first. It was quite rewarding to get it done (the best tailored product is the one you develop for yourself) - but still with a sensation of quite absurd oddity, since I had been using full-fledged word processors in the early nineties, and "there I was", almost thirty years later, with tablets much more powerful than the desktops of yore, coding a word processor because all was available for Android was unfit for use if compared to desktop tools, and I was just losing time waiting for "the product"... It's not "normal".