You’re welcome! The presence of exotic plant species doesn’t kill specialist native pollinators; the lack of native plant species kills off specialist native pollinators. Invasives only need to be removed because they outcompete plants of higher value to the ecosystem.
If you’re in North America (just guessing based on tumblr demographics) dandelions have been here for 400+ years. At this point their presence is primarily an aesthetic concern for people who grow turf grass monocultures; they love open, sunny, newly disturbed sites, but get shaded/crowded out in more complex ecosystems with native trees and shrubs, so as far as I know, they aren’t much of a threat. Maybe a concern for people trying to maintain a wildflower meadow? I’m not sure.
If you can’t eliminate the knotweed (challenging and time-consuming, will involve herbicides) you can try cutting it back annually before it flowers, to reduce its ability to spread by seed dispersal, which your neighbors may appreciate.