https://gamerant.com/ghost-recon-breakpoint-steam-pc/
Like previous Ubisoft titles’ Anno 1800 and The Division 2, Ghost Recon Breakpoint on PC will only be available on two platforms: Ubisoft’s service Uplay or the Epic Games Store.
Which means, like the previous games that were only on Steam and uPlay, they're actually just on uPlay anyway and you should just buy those keys unless you're weird.
uPlay keys are still wildin out all over resellers constantly getting discounts so this is the least concerning set of Epic Game Store situations. Especially since you don't need EGS at all.
Since I re-purchased Rainbow Six Siege to get out of launcher/file recheck/etc. hell with Steam/uPlay and upgrade from the starter edition it's like with Origin, a one publisher situation now for me. Only, that uPlay keys are sold basically everywhere. So it's better than Origin usually. Also ubisoft remembers more often that they have a back library to toss out for $2 every so often.
uPlay also autodetects versions from elsewhere like GOG. So like if I wanna install and play Prince of Persia: The Sands of Time or even 2008, I just install it on GOG, and it's there in uPlay and just launches the game as if it was GOG but with the uPlay overlay available. (2008 doesn't work with the Steam overlay and never has for some reason.) Register your Steam keys and you get "clean" uPlay installs on your account. You couldn't run the Steam versions after ACII without uPlay anyway.
uPlay is arguably the second best option after Steam since they sell the keys elsewhere and anywhere, GOG keeps those close to the vest for obvious reasons, so like Origin, I'll bump uPlay up a tad, especially when they dump keys on me through Humble.