No, your bathroom needs a whole lot more than a new shower. That incredibly dangerous white whale needs to GO. You need to hire a K&B Designer to rework the whole goshdarn thing.

I'd consult a designer to get ideas for the whole space as I don't find stairs and tubs safe or practical.

If this were my bathroom, I’d save up for a year or two to do a more comprehensive remodel. Otherwise, you’ll pay many thousands to build a new shower, which is quite small, and get nothing else, still left with that large and dangerous tub. If you save up, you could get a larger shower, and a new drop-in tub with deck surround. The tub area would be a bit smaller so your shower could be a bit larger.