They have a good idea with the engine-driven hydraulic power pack. Except that you can buy those cheaply enough that making them isn't worth the trouble.[1][2] All they're really making is the frame; the engine, pump, hoses, radiator, and controls are all purchased.
(Those guys seem to have a thing about not painting metal, so that it Looks Hand Made. Bare steel rusts. Rapidly. Paint is cheap.)
[1] https://www.ebay.com/itm/STANLEY-GT13-HYDRAULIC-POWER-PACK-S...
[2] https://www.alibaba.com/product-detail/Mini-order-Hydraulic-...
This is something that bugs me probably far more than it should. I'm really sick of seeing half-assed implementations of stuff that you can buy cheaply off the shelf. Don't people do research before starting to design things anymore?
It's pretty rare that you can build something for less than the equivalent off the shelf item. Now, if that item is missing a feature you need, that's a different story.
https://www.opensourceecology.org/