Actually most zip ties are releasable. Most require the use of a small tool to depress the locking mechanism while extracting the end. I've used zip ties extensively for the past 25 years. The best were coated metal strap type that I used mostly for tying heliax to the sides of towers. I still have a handful of them in one of my bags. You could just about use them for choking logs off a mountain, they are pretty tough.

Get black ties rather than white, they hold up to the UV better. One thing to remember, there's no such thing as a zip tie that's too big, but you can get them too small for a task. If you do, be aware that they can be daisy-chained together to make them longer.

As for what to use them for, use them for lashing a skein of line up, or extension cords, or locking two sticks together either in parallel or perpendicular for framing work, or a green branch into a loop, or lashing branches to framing to make walls or roof cover, or splicing line without knotting it up, or as stitching along heavy seams like canvas or leather or as a bag end closure, or as emergency shoe lacing, etc.