Who cares who develops it first.
Fusion will generate power for the whole world, and it will be the end of basically all coal power plants. This will benefit EVERYONE.
Fossil fuels won't go away from one day to another tho. It will take forever for all countries to transition to basically infinite electrical power, and we don't have enough EV's on the road just yet to replace oil. Then there's planes, ships and trucks we need to look at.
So who cares who develops it. China at least will provide it for the people, while the US will stall it to sell more oil.