There’s the MWC web wallet which is self-custodial and works with Grin, Epic Cash, and MimbleWimble Coin. https://mwcwallet.com?Override+Wallet+Type=Grin
It works on desktop and mobile, and it has support for Ledger and Trezor hardware wallets when accessed via web browsers that implement WebUSB or Web Bluetooth.
It’s also available as a browser extension for Chrome, Firefox and Safari which has the added ability of allowing websites to open the wallet to prompt the user to approve sending a payment. https://github.com/NicolasFlamel1/MWC-Wallet-Browser-Extension