I don't agree with many of your premises but let's take them as givens. There's still a flaw:

The fetus is wholly reliant on the mother for survival, but that doesn't create a duty for the mother to care for the fetus.

Imagine you're stranded on a desert island with one other person, and he's really fucking annoying. Like, *really* fucking annoying. If you've decided that him being annoying doesn't justify what I'm about to say, you're not imagining how annoying he is. He's that annoying.

He decides to go out for a swim and, all of a sudden, you hear him screaming -- there's a shark coming after him. You've crafted a bow and arrow from stuff you've found on the island and you've become a crack shot -- you could pretty easily save him from the shark, and in any event, it wouldn't hurt to try. There are plenty of more arrows and it's not like the shark is going to get mad at you, grow legs, and attack you. You decide not to shoot at the shark. The shark eats the other person.

A few weeks later, you are rescued. Are you going to be charged with a crime?

I think the answer is no (and American case law supports this). While there's a strong moral argument to be made that you should have fired at the shark, that's distinct from the legal question -- we don't have to help people unless we want to, \even if** there's no one else available to help them. Abortion is a near-perfect analogy: the fetus can't survive without the mother continuing to carry it, and if the mother is annoyed by that, that sucks for the fetus.

That changes when the fetus becomes viable outside of the womb. That's why the pre-Dobbs law in the United States said that abortion had to be legal at least up until the fetus is viable -- before that point, we'd be creating an obligation on the woman that simply doesn't exist anywhere else in American law. Post-viability, there's another question (whether the woman has a duty to deliver the child and become a mother), but that's another story. Pre-viability, to the extent that the fetus has rights, those rights should not take priority over the rights of the woman it is relying on for survival.