You don't need bombs to ground jump to to the chest, you can do an
angled jump to the upper ledge. You would still need a chu to megaflip to the chest.
The fastest route would probably be
-intro
-10r, buy stick (maybe 2?)
-aquascape
-kak
-botw, chus (nuts might be fastest here)
-a slide out of kak
-a slide to gv
-chu megaflip over gate
-climb up gf, megaflip to mush