Good luck on finding a i9-10900K in stock.
If budget is not a problem, go ahead and buy the 10900K.
It is a better binned chip and will turbo up a bit higher to 5.3
If you buy a high end Z490 based motherboard you will have more options and the ability to overclock later should the need surface.
Still, the i9-10900 is a very strong processor.
For that, you might want to save a bit on the motherboard and use the budget elsewhere.