I can't speak to the synapse part of your question but the OP covers the hot key to swap between winkey and alt. If you stick with winkey you're going to have to use PowerToys or regedit to disable the default windows behavior for those key strokes.
If you're willing to give up using ALT+1-5 for key binds in game, ALT is an easier hotkey to work with as compared to winkey.