The whole set of machines looks like something China's ministry of agriculture would have come up with around 1980 or so. There are some standard items widely used in rural China and India, manufactured by many manufacturers. Here's a small Diesel engine.[1] This thing is brutally simple - one cylinder, non-recirculating water cooled (you have to add water when you add fuel), hand crank start, no emission controls. Costs about US$300. There's someone who has a YouTube channel of fixing discarded engines of this type. There seem to be a lot of them lying around, all very similar but from different manufacturers. It's the AK-47 of Diesel engines - it's crude, it Just Works, and it can be fixed. It's mass-produced, because making metal parts in quantity is very efficient, while one-offs are too labor intensive.
Here's a basic tractor, the Wuzheng TS, costing around $6,000. "Mature technology", the maker says. There are hundreds of thousands of those things in the Third World.
That's how this gets done in the real world. Mass produced machines of similar design that's proved itself. That's how the US did it, back when the Fordson tractor [3] was popular. Ford produced low-end tractors until 1964.
You can still buy low-end farm equipment cheaply. It's not cost effective for a commercial farm, but it's still available. Sometimes it's all you need.
[1] https://toppower.en.made-in-china.com/product/kmtRnxhrTvpB/C...
[2] https://chinawuzheng.en.made-in-china.com/product/ovGERBPVaa...