And compete with the vast network of superchargers Tesla's already established for themselves...
And in fact will soon have more 350kw chargers than Tesla.
Ionity is installing 350kw chargers in Europe: https://ionity.eu/en/design-and-tech.html
And so is Fastned: https://fastnedcharging.com/en/blog/post/fastned-opens-its-f...
Anyways, it's a good thing for the whole electric vehicle ecosystem that multiple charging options become available. That multiple companies are competing on charging infrastructure is excellent!
Not yet. The Porsche Taycan is launching with 250 kw charging (with 350 kw charging to come in future) but I haven't seen any information on its charge curve. The Tesla Model 3 can charge at 250kw to about 20% state of charge and then it progressively drops off.