Barry, I’ll throw in a couple things. I’ve worked in and around wood for a long time, and I can tell you some of what works and what doesn’t.
I’ve tried splitting rounds and cutting up chunks. It’s time consuming for what you get. Yes a machine could be built, for a lot of money/time invested. But usually this same firewood is much more valuable to someone heating with wood. Why take a high value fuel and chop it into tiny bits? Start with a feedstock that’s closer to what you need. Every woodgas driver here uses waste wood scrap, not full size rounds.
Anyone processing trees into firewood generates an equal volume of brush, usually discarded. This is where you come in. All the wood from 3" down to 1" diameter is gold to you and your gasifier. They don’t want or use it, so you can get it for free in full lengths, ready for chunking. You’ll want a small chainsaw and a good pruner/lopper to clean up the bits you want. Leave the smallest bits for the brush pile, or use a chipper/shredder to mulch it. I did this myself for several years living in town without a steady wood supply of my own - just followed the tree trimming folks around and skimmed what I wanted.
Get a small sawmill going. They can be build relatively cheaply. You’ll have a dependable income stream, if you can handle the work. The slabs (waste wood from making a round thing square) will be simple to chunk - Wayne does this almost exclusively, and heats his house with them too.
Coppicing. Small saplings come up very quickly and are nearly the perfect size for your chunker, long and straight with few branches. In Europe this is a primary source of fuel wood. In those rebak-style chunkers you see on Youtube, the feedstock is mostly these type of saplings. If you have a woodlot you can manage, this is dead simple. You can also feed prunings into there. If there’s an orchard nearby, they will have piles of prunings about the right size.
Lastly, I’ll clarify the sentiment in the first part of the thread. Part of our job on this site is to get folks off their rear and into building a working gasifier. So expect some pressure in this direction. It’s all good natured of course.
You (like me) are prone to research everything in depth and make detailed plans before you start building anything. The danger is, you can spend your entire life designing and refining an idea that may never get built. We see it all the time. The more cool and technical sounding their posts online, the less seat time they’ve probably had (there are exceptions of course). You can join the crowd of thinkers. Or you can build something that works.
Better to build a boring, normal gasifier first, than try to build your ultimate setup right out of the gate. Nobody does that. Wayne has built over a dozen trucks. Every experienced woodgasser here is on their second or third build (at least).