I have no problem with Leia using the Force to get back to the ship. It doesn’t require mastery of the Force, just a little nudge really, since moving in vacuum and zero-g doesn’t take a lot of force. Probably less Force is required than for pulling out a lightsaber from the snow for an untrained Luke. And being near death is the perfect occassion to manifest every last bit of your abilities - that’s true for every human.

Also, it is possible to survive in vacuum for a minute or so. See here: https://www.scientificamerican.com/article/survival-in-space-unprotected-possible/. Therefore this scene didn’t bother me at all upon my first viewing, and trust me, there were quite a few scenes that did.

Maybe the scene can be moved to immediately after the explosion to imply that she spends very little time in vacuum and cut out the bit where she is unconcious?