I'm not sure what the e-ink requirement does to your search, but I write on my Samsung Galaxy 10A (2019) all the time using a BT keyboard case and BT mouse. I didn't know about the 10.1-inch requirement for MS office on Android tablets. But it works very well.
Have you looked at yWriter for Android? It costs $5 US, and it isn't quite the app that the Windows app is, but I have it, it's OK, and works well.
I know you have rejected online apps but I think Wavemaker is very good. It's free, works with a free Google drive account and is VERY reliable.
BTW, it works offline as well.
WaveMaker Cards