That is a pretty cool rig.
There is a local nursery where the owner zips around on a Segway with big mudder tires. Similar idea to the rig in your video.
As far as a battery outdoor tool system you might want to check out the system that Stihl offers. IMHO the hedge trimmer I bought two years ago is more than adequate for a home owner with a large yard and 20+ bushes to trim. For example, the first day I used it I charged it the night before. I trimmed for 2 1/2 hours. Stopped for lunch. I put the battery on the charger and it still showed 2 out of 4 bars. When I started up again an hour later it was fully charged and I used it for another 2 hours. When I was done, I sprayed the blades with a cleaner and hung it back on the wall of the garage. I put the battery and the charger back on a shelf in the basement. No worries about the carb plugging up because of ethanol fuel. No concern about keeping gasoline in the garage, etc. We are all familiar with the ethanol small engine problems.
Also, the Stihl hedge trimmer was made in Austria. The battery was made in Germany. They may be making these in SC now. I purchased the largest battery for this series of tools. As I mentioned earlier, the battery and charger were $100.
One of the things I realized after using a battery operated tool like this was that when you are not actually cutting with it, you release the trigger and it stops. Where as a gas engine you keep it running constantly even when you are walking from one spot in the yard to the next. This reduces the actual run time of the battery significantly. So, even though I was out in the yard for 2 1/2 hours trimming bushes, I was probably only cutting for a third of that time or less.
The military possibilities are many.
I am all in on battery operated tools at home, just want something I can go to local store and replace at a decent cost. I don't insist on Dewalt or Festa, I use over the counter stuff from big box store. Years ago I just decided to use Sears tools since they would always be there, oh well. I currently am using Ryobi because they are reasonably priced and more than adequate. They just had there $100.00 battery pack deal two 4 amp batteries and a charger plus a free tool, bought 3 of them. I have tools I will likely use once in my time remaining, like to pretend I will live forever I guess.
I have my eye on the new zero turn mower from Ryobi just for yard, finally put some goats on the biggest portion of land I have to mow. They are not natural grazers but they do a pretty good job. Chickens will turn a pasture into a mud hole if you let them.