Nova launcher works pretty well, with the "Black iconia" icon pack, and white background.
Stylus Beta - which gives handwriting input - works fairly well.
Of all the filemanagers I tried, Total Commander works best for me. X-plore is not available.
ghost commander is also very nice (switch background to white and foreground to black)
xodo docs works, with 'Stylus as pen" turned off. The stylus is fairly slow, but I think that pages are drawn faster than in Neo 2, though they don't look as good.
WPS works quite nicely, though it is a bit slow. Pen annotation work when one selects "use finger". What I haven't figured out how to do is zoom. It seems one can only zoom with two finger gesture. Is there some trick with which one can do this? Should I by a second stylus?
(Microsoft excel says it is incompatible with the device, as does google sheets. Why is that?)