@c-los I’ve never done it, so I don’t know how it’s done, but I know you can add Steam to Lutris.
Other option can be installing protontrinks, which is winetricks for steam-proton games. There you can see your games installed with proton, select them and run winetricks for them. You can also do other actions on that prefix.
Edit: there is another option. You can point the Lutris wine prefix to the Falcon4’s proton one. Maybe you also need to select the Flacon4 folder? Not fully sure about this.