I sometimes help out at a hobby vineyard of 0.7 hectare; weeding in the row is a lot of manual labour. Your platform seems like a good fit. I like tinkering and robotics, what kind of price point are you aiming for?
a simple ride on mower with a diy inter row disc (basically just a belt and pulley with a spring) may be enough. probably just get sonebody with a tractor and inter row disc weeder to do the job for you.
In my head it's £3-£5k, so by the time it's useful probably a bit more than that.