There are many different niches of ML. 99% of hobbyist would use consumer grade hardware. It’s quite frankly more than good enough.
Even in commercial usage, consumer GPUs provide better value unless you need to do something that very specifically require a huge vram pool. Like connecting multiple A100 GPUs to have hundreds or tens of thousands of gigabyte vram. Those use cases only come up if you’re making base models for general purpose.
If you’re using it for single person use case, something like 4090 is actually the best hardware. Enough ram to run almost anything and it’s higher clock speed than enterprise GPU means your results come back faster.
Even training doesn’t require that much vram. Chat models are generally more vram heavy but if you’re doing specific image training like stable diffusion for how to render your face, or some specific fetish porn, you only really need like 12GB of vram to do it. There are ways to even do it at lower like 8GB but 12 is sweet value spot where even 3060 or 4060ti can do. Consumer GPUs will get that trained in like 30min to 24hrs depending on settings and model.
12v boat motors are for only trolling. So technically it powers a boat, but not really… They’re typically only 1hp. You could get a 1hp AC, but they’re not designed to run on 12v. You’d need to change DC to AC and then step up to 120v at least.
You’d run out of power pretty fast either way if you’re planning to use the AC for extended period of time, just like trolling motors. And no quick way to recharge. Alternator suggested above is somewhat realistic as some cars actually do come with a 120V outlet (albeit at limited wattage not enough to power a full sized window AC). Though, all of this is rather inefficient setup and burning more gas.