Elephant Song (1994)

Coffee-shop waitress Kanako, divorced with a young son, finds herself obliged to honour a rash promise she made to a long-time customer. He always wanted to be buried in the land rather than a cemetery, so that his body would be 'useful' - and now he's dead. Kanako and her boy enlist the help of a friendly florist with a small truck, steal the corpse, and head for the mountains.

Unfortunately the movie Elephant Song is not yet available on HBO Max.