You can download the digital version directly to your Switch.
Downloading ROMs may be against the law in your region, and it can also harm your device or compromise your data. We encourage gamers to support game developers and purchase the game through official channels. sonic frontiers switch rom download link
If you're interested in playing Sonic Frontiers, I recommend checking out official channels for purchasing or downloading the game, such as the Nintendo eShop, to ensure you're getting a legitimate copy. You can download the digital version directly to your Switch