Just a few observations: most knives are not made for heavy prying. The ones that are tend to be very poor cutters. If the knife is sturdy enough to be used as a prybar the blade/point might be too thick to wedge it between something like a doorframe for instance.

A real prybar is never fully straight. The tip at least is usually at a slight angle. That's important because it gives you some leverage that a completely straight tool cannot. Also very helpful for getting into tight spaces and such.

Modifying a machete would not be a good idea. A typical machete is very thin and springy. Even if you cut it down it will flex too much when prying. If the blade doesn't break the handle scales will. On the other hand, a sturdy billhook or Woodman's Pal might work, very versatile, but it is a pretty large tool.

Then the question of material. The Boker Cop Tool for instance is made of 440C. As a rule, stainless steels are unsuitable for prying tools because they are too brittle and lack the necessary toughness.

All in all, I wonder whether it wouldn't make more sense to get several smaller-sized tools that would cover all your needs much more reliably (small prybar, chisel, maybe a large flat-head screwdriver... I reckon you probably EDC a good folder and/or multitool already). It would be a more reliable option, maybe even cheaper. If I had to pick just one alla-round tool though it would be the hacking knife (check out Corpsman's link).