Hi!
Did You find something regarding battery-pack (hand-grip) for 801s?
As far as I know, Nikon never made any battery-grip either for 801 or 801s; but maybe, some under-brand did it.
801 might get MB-10 (battery-pack of F90 and F90x), but it does not fully close to the bottom plate; screw goes in, yet.
I found as a fine and useful accessory, the MF-21 Multi-functions data-back and it is easy to find it as inexpensive, too: since 801 and 801s went (wrongly) less researched over the years, this Data-back too, had less market; but there are several (used or unsold-new) MF-21 (or 20) around, still!
Greetings from ITALIA !