Fallout 76 has been exclusive to Bethesda's own launcher for quite some time now, but starting with the release of the Wastelanders update, which will be bringing factions, reputation and human NPC's to the game, the game will also be launching on the Steam platform.
To be fair, those who've held out all this time will be getting a much better game overall than we got on Day 1. Honestly though I find myself rarely ever coming back to Fallout 76, but I hope the Wastelanders update might change my viewpoint on things.
The official launch date is the 7th of April. There's a new trailer above too, showing off what you can expect in the Wastelanders update, including the Raiders, who are camped out in a crashed space station, and the settlers, with their new settlement known as Foundation.
If you want to switch from Bethesda's platform to Steam though, you're out of luck, as you won't be able to transfer any Atoms or membership balance between the two versions.