AFAIK Rollup can't do part-combinations, gotta code them. Is this what you mean?
select
dealerid,
item,
unitid,
district,
user,
concat(user,'_',district) user_districts,
concat(dealerid,'_',district) dealer_districts,
concat(item,'_',district) item_districts,
concat(item,'_',dealerid) dealer_districts,
count(user) users,
count(district) districts,
count(distinct district) distinct_districts,
count(distinct concat(user,'_',district)) user_dostricts,
count(distinct concat(dealerid,'_',district)) dealer_districts,
count(distinct concat(item,'_',district)) item_districts,
count(distinct concat(item,'_',dealerid)) dealer_districts,
count(distinct item) items,
count(distinct dealerid) dealerids
from testrollup
group by dealerid, item, unitid, district, user, user_districts, dealer_districts, item_districts, dealer_districts
with rollup ;