Can I use freestyle boots with touring bindings for backcountry access?

Generally no. Most freestyle boots lack tech fittings (pin holes) required for tech/touring bindings and don't have walk mode for efficient uphill travel. They're also heavier than touring boots, making skinning exhausting. If you need backcountry capability, look at freeride boots with walk mode and tech compatibility instead. Some hybrid models exist, but they compromise on both park performance and touring efficiency.