Ubisoft has its own Uplay launcher, which regularly releases its games on the PC. However, they did not bypass the Steve service from Valve. The coming The Division 2 will change this situation.
The publisher officially announced that the game will not be available on Steam. You can buy it on a PC in the Epic store and in the company's Uplay store.
However, there is a possibility that this transaction will be temporary, and in the future The Division 2 will still appear in the store from Valve. However, no specific information on this matter yet.