I've experimented with bundling twigs and tying them. We have lots of native NZ
flax (Phormium tenax) and the leaf fibres are amazing. The best results I've had were with standing dead trees or branches with lots of small twigs. I cut them, left them on the ground in the paddock, and then when they were wet and pliable I tied them as tightly as I could with flax. Then I cut the bundles to firewood length and tossed them into the woodshed to dry.
These bundles act a little more like "normal" firewood, but there's still a lot of surface area and I wind up with a pretty hot burn unless I close down the damper on our fire (a clean-air design mandated in NZ for at least a decade now which avoids smoldering banked fires that smoke the bejeezus out of the town on cold nights). Verdict: more trouble than it's worth for me, and these days all our twiggy stuff either gets used as kindling or goes back to the soil.
You might give it a try this winter when everything is wet and pliable. Bundles don't take long to dry as long as you start with dead twigs. No reason you couldn't just use twine if you don't have flax.