All games can extract and convert the models, not only valve games.
Already i have convert :
Valve games
Metro 2033 - Metro Last Light
Dayz Standalone
All games with Unreal Engine like DeadPool - Life is strange - Kholat - Alone in the dark - This war of mine - Betrayer etc..
Probably 70% of games on steam can convert.
About the models unfortunately I do not have much time now sorry guys.