There are no federally elected democrats who espouse the position of open borders. None. Zero. Every single member of the democratic party in office today in federal office supports some degree of border control, and frankly the degree that they want is not worlds apart from what most republicans want.
The GOP has successfully planted the idea that they are for a wall that lets no one through and the dems will let everyone in, but it's much more like two sides bickering over whether the wall should be 10m or 15m tall, whether or not there should be razors at the top, and exactly how many palantir/anduril terminators should be purchased for intercepting people, 1000 or 1200.