Mobile — Wear, TV, Auto, VisionOS

The "extended mobile" surfaces — wearables, TV, car, mixed reality — share toolchains with their phone counterparts but each has its own constraints. For phone development see iOS and Android.

Apple ecosystem (one Xcode, multiple targets)

• ★ watchOS 11+ — SwiftUI; WatchKit is legacy. WidgetKit + ActivityKit (Live Activities surface on watch). Independent and paired apps.
• ★ tvOS — SwiftUI; focus engine for D-pad navigation; Top Shelf for surface integration. Apple TV 4K only.
• ★ visionOS — released 2024; SwiftUI + RealityKit + ARKit anchored. Volumes, Windows, Immersive Spaces. Vision Pro-only as of 2026 (cheaper Vision lineup rumored).
• ★ CarPlay — entitlement-gated app types (Audio, Communication, EV charging, Maps, etc.); not open to everyone.
• Mac Catalyst / SwiftUI on Mac — bring iPad apps to Mac; not "wearable/TV/car" but the same one-codebase story.

Android ecosystem

• ★ Wear OS — built on Android; Compose for Wear OS is the default UI. Material 3 Expressive Watch.
• ★ Android TV / Google TV — Compose for TV; D-pad-friendly Material widgets.
• ★ Android Auto — projects from phone to head unit; entitled / approved app categories (media, messaging, navigation, parking, charging, IoT).
• Android Automotive (AAOS) — full OS in the car (Polestar, Volvo, Honda, Renault); your app runs natively in the vehicle.
• Pixel Watch / Wear OS 4+ — Pixel Watch and partners.

Samsung-specific

• One UI Watch (Wear OS-based since 2021) — Samsung Galaxy Watch 4+ uses Wear OS underneath.
• Tizen — older Samsung wearable OS; smart TVs still ship Tizen; check current support.

Cross-platform on extended surfaces

• Flutter on Wear OS / Apple Watch — limited; community plugins; not stable production targets.
• Flutter on Android TV — works; Compose for TV is the safer bet.
• React Native on Apple TV / tvOS — community-maintained react-native-tvos fork.
• React Native on Wear OS — community plugins; not first-class.
• Compose Multiplatform — runs on Android Wear / TV via Compose; iOS targets aren't watchOS-aware.

VisionOS specifics

• RealityKit — 3D scene composition.
• ARKit — anchor scenes to real space.
• Reality Composer Pro — Xcode-bundled scene editor.
• USDZ — model format.
• See 3d-format-converters, 3d-webgl for adjacent 3D pipelines.

CarPlay / Android Auto entitlement reality

• Apple requires CarPlay entitlements per app category; review-light for approved categories, hard wall otherwise.
• Google's Android Auto / AAOS app categories: similar gate-keeping; messaging / media / nav / IoT / parking / charging only.
• Don't build a custom app for cars unless you're in one of these categories — you can't ship.

Distribution / store specifics

• App Store for tvOS / watchOS / visionOS — single Apple Developer account; separate target binaries.
• Play Store for Wear OS / TV — same console; separate Android Auto / Wear OS app categorization.
• Galaxy Watch Store / Galaxy Store TV — Samsung-specific listings.

Pick this if…

• Companion watch app on iOS: SwiftUI watchOS target.
• Standalone watch app: SwiftUI watchOS independent target or Compose for Wear OS.
• Smart TV app: Compose for TV (Android side) + tvOS SwiftUI (Apple side).
• In-car experience: evaluate CarPlay / Android Auto category; or AAOS native if you're a manufacturer.
• Mixed reality (visionOS): SwiftUI + RealityKit; cross-platform 3D ports are unrealistic in 2026.