Property 'ethereum' does not exist on type 'Window & typeof globalThis

結論

(window as any).ethereum

Property 'ethereum' does not exist on type 'Window & typeof globalThisで、型エラーを直そうと

window.ethereum as any
とか
import { MetaMaskInpageProvider } from "@metamask/providers";
declare global {
interface Window{
ethereum?:MetaMaskInpageProvider
}
}
とか
interface Window {
ethereum: any
}
とかやってみたけど、

(window as any).ethereumで一旦解決しました。