[Syonyk]

No. Or, at least, not easily. The high voltage battery isn't generally connected until "the computers are happy" with the state of things, for various hybrids/EVs/etc.

There's also a legal requirement that "marker lights and such" still work (presumably, also power locks and such) after a prime mover failure. Basically, if the engine quits, you should still be able to signal, get over, turn your 4-ways on, etc.

The easiest solution is to just put a lead acid 12V battery in the car for that. Lithium, in particular, is a problem below freezing because you can't safely charge it, whereas lead doesn't have that problem.