Electron is certainly an option, albeit a somewhat inefficient one. A "dangerous" web-decker build could use custom JS extensions to possibly handle steam integrations, I guess?
The normal Decker executable can be given a startup deck or launched with command-line arguments (which could be supplied via a script or batch file). Anyone is welcome to re-distribute my Windows or MacOS executables for the purposes of shipping their decks. Using app.save[] to preserve state would work in this scenario, though you'd probably want your deck to include some way to reset your game or program to a factory default.
With more effort, you could build Decker from source and replace "/examples/decks/tour.deck" to make a Decker executable that always loaded your deck on startup without accessing any external files. A "dangerous" build of native-decker could use danger.read[]/danger.write[] to preserve state silently. Going this route would also make it possible to add in custom steam-specific interfaces, but you'd have to get your hands dirty writing C. Compiling Decker on Windows is a real pain and I do not wish to tutorialize or offer tech support for any aspect of the Windows development ecosystem.