I find the idea of the portable power fascinating and have watched some YouTube videos on them, but it seems like a very expensive and niche thing so far. I've seen one company on YouTube that showed it off.
I wanted an EV since back when I lived in an apartment, wished there was some sort of big capacitor on wheels I could charge all day from a normal outlet that would then fast charge my car for a few minutes.
Most actual products seem to use batteries and cost thousands, and are for some unique scenario where you somehow can't just public charge. Still find them neat though.
I think they typically just tow you to a charging station, seems a lot easier/faster/cheaper given they already own tow trucks.
In my opinion the only cost effective battery to travel around with would be the one inside an existing EV, I just hope we get beyond household outlet speeds for V2L. Would be neat if a passing EV could rescue at 50kw or something fast.
It's also true that running out of gas doesn't require a tow. You just need roadside assistance to bring 5-10 gallons to get you back on the road in minutes.