Suggestion: Add a "Completed" tag and option to hide completed games from the main library list (especially on Steam Deck)

I have over 200 games in my Steam library and there is no convenient built-in way to separate completed games from those I still want to play.

I know about collections and I use them, but there is an important issue, especially on Steam Deck:

On PC and in Steam Deck desktop mode, when I move games to a collection and hide them from the main list, they actually disappear from the general library view.

In Big Picture / Gaming Mode on Steam Deck, these games still appear in the main library list, even if they were moved to a collection and hidden in desktop mode.

As a result, in Big Picture mode I still see a lot of games I have already finished, and it is harder to find the ones I actually plan to play.

What I’d like to see:

A built-in flag per game, like "Completed" / "Finished".

A filter/option in the library (especially in Big Picture and on Steam Deck) such as:

Show only not completed games

Hide completed games from the main library list

Alternatively, make the behavior of hiding games via collections consistent across all modes: if a game is hidden/removed from the main list in desktop mode, it should not appear in the main list in Big Picture / on Steam Deck.

Why this would be useful:

Easier navigation in large libraries (200+ games).

Lets Steam act as a simple progress tracker: what is completed, what is in the queue, what is in progress.

Especially useful on Steam Deck, where you want to quickly see only the games you haven’t completed yet, instead of scrolling through everything you already finished.

I think many users with large libraries would appreciate a native way to manage completed vs not completed games, without workarounds via collections or third-party tools.