I've been trying to recreate this simple arp from one of my favorite wave songs and I feel like I've gotten pretty close, but it's not quite there yet. In Serum I used a square wave with a fast LFO (retriggering at 1/128) on the coarse pitch to achieve the gritty effect, but maybe there's a better way to do it. (The sound starts at 0:12)
Here's my attempt at achieving the sound.