What to do w/ straight up Dyneema rope?

https://westcoastsailing.net/line/dyneema-spectra-vectran/

Maybe a good light weight pull cord?

Petzl make the rad line

https://m.petzl.com/GB/en/Sport/Ropes/RAD-LINE-6-mm

Petzl pur line 

Don't go too thin. I use a different version of the 1.7mm line as a throwline for arborist work and it will easily cut the crap out of you if pulling hard on it bare handed. 

The common hollow braid spliceable dyneema ropes used in sailing are not that great for climbing, its too easy to open up the rope, catch a single strand, etc... A tighter weave that can't easily open up is better suited to climbing use.

They also suck to pull. You can't really use your hands, too thin. Either Garda hitch to your harness and walk backwards, or do a carabiner spine wrap to add friction (but you still must hold the line below this tight or it will slip) and use the carabiner as a handle to pull.

I had a situation where I had to do a 3:1 on a thin, badly coated dyneema pull cord where I had to employ these tactics on top of the 3:1... so I'm a bit salty on hollow braid by itself.

I have Lots of tech12 and it come in handy all the time in my professional rigging world.

for climbing... I've thought about making some quick draws that are spliced tech 12 of custom lengths. 

Maybe it would work for the Zed cord on a 2:1 big wall hauling rig.  Does it play nice with pulleys?

Its extremely useful in rigging. Highliners often use the stuff to build anchors and make connectors. Sometimes they're used to backup lines. Not much use in climbing that I can think of however.