You can still get the engines, batteries, controller boards, cameras, transceivers, gyro sensors, propellers, screws, cables, ... from china without problem. You just need to do the assembly yourself. I guess that's no loss because most probably Ukraine wants to mod the drones for their military needs anyway. So in reality that's barely news, the only effect I can imagine might be a slight annoyance for volunteer units and self-organized donations. They now can't use off-the-shelf DJI drones but have to go for brands that do the final assembly outside of china.

High strength magnets require a non-trivial amount of infrastructure to produce, but mainly they require rare earth elements that china is already restricting the sale of. This seems like a move more to do with the tarrifs than Ukraine though, since as the other commentor pointed out, you can still get all the parts.