> So one can get the installers for these games through Steam and use them without running their client and etc.

Yes, that is the case case with the DRM free Steam games I have played. I guess that this is common among indie games at Steam, but I have not really looked into it.

> Is there an easy way to filter games by this criteria on Steam itself?

Do not think so. I do not think Valve want to dissuade developers to use their DRM.

Unfortunately no Steam uses its own package format, so it must run the installer the first time to get steam to unpack it. Steam provides DRM but it is up to the author of the game to use it, their own, or none as they see fit. And no Steam doesn't provide any clues as to what DRM is used by a game.