MetaMask Snaps is a way that developers can bring, well, anything they can put into an API into MetaMask. That includes non-EVM compatible cryptography. That includes custom functionality. That includes that crazy idea that you just thought of. And yes, it includes being able to access and control your Bitcoin through MetaMask:
Currently available only in the developer-only MetaMask Flask, but coming to Production MetaMask soon.
If you’re creating a dapp that you’d like to deploy to non-EVM networks, building a Snap allows your users to interact with your dapp while benefiting from the feature-rich, familiar MetaMask environment. Take a walk through our Network Node for more considerations about choosing a deploy network.
Given their flexibility, Snaps represent an entirely new horizon in web3 development; they also represent a significant challenge to user safety. Snaps can currently only be accessed through MetaMask Flask, a distribution of MetaMask meant for developer testing only.