Yeah games I would consider to be Gaas are some of the ones you mentioned, like Destiny and Anthem, also Fallout 76, upcoming games like (I imagine), Outriders. Also I consider Paradox games to be good examples of singleplayer games as a service, with Europa Universalis 4 exemplifying the case.
Fortnite and Apex and CoD:Warzone and such games I think are better described as "free to play" since I think that carries with it the understanding there will be microtransactions, "battlepasses", boxes and other such items.
So in that light i'd define a Gaas a bit more strongly than you do. A paid-for game which releases significant gameplay content that affects the base game behind a paywall.
Some games do this very badly (like the original Destiny) which seemed to release as a kind of £50 prologue. Some games also make players who don't pay up for the next big title update feel like second-class players, with DLC map areas obnoxiously greyed out to devalue the original content. But some games do it very very well. EU4 is one of them. Their DLC introduces significant changes to the way the game plays, but not buying it still leaves the original mechanics in the game and leaves no trace of its absence.
This means that games mentioned here like..
Animal Crossing (no paid expansions)
Gears 5 (cosmetics only)
Smash Ultimate (cosmetics only)
... wouldn't properly qualify as games as a service in my book.
