There's a couple god abilities that increase move speed from lightning/time god. Also movespeed on boots. Items and character traits are the only meta progression so far and there's a stash if you didn't see it to share amongst all the characters.
That's pretty much all DmD has to offer right now. They recently released a road map and are looking to release the next area and tier 2 equipment and another god.
That's not bullet hell, its a newer genre called bullet heaven or enemy hell. Swing by this thread for some good recomendations
https://www.firesofheaven.org/threads/roguelite-enemy-hell-bullet-heaven-survivor-catch-all.14200/