>Buy some old EV batteries wire them up and you can make anything with wheels move. Including really old tractors, pickup trucks, etc. Anything from the largest mining trucks to the smallest lawn mower can already be powered by batteries. And everything in between. With battery cost dropping, there are very few obstacles that prevent adoption left. Mostly import tariffs in the US.
It's not even close to that easy though is it? I've wanted to convert a car to an EV and it seems really complex.
What car? It probably depends on what you want the end result to be. You won't be able to DIY a Porsche Taycan, but basically if you can do an engine swap on an ICE car, you should be able to do a semi-ghetto EV conversion (i.e no fast charging or advanced thermal management, but safe and robust enough to run daily for years). Tons of people are doing it on YouTube.
Of course, there is a bit of skill involved and I don't claim to be able to do this. But then, putting together a combustion engine would also require a bit of skill. Lots of parts that need to be fitted together. Hoses, pumps, wires, and a lot of electronics as well with more modern cars.
EVs have less parts. There are some challenges with diagnostics for things like battery management systems. And given the high voltages, it helps if you know what you are doing with electrical systems.