I believe the nostr:nprofile1qyxhwumn8ghj7mn0wvhxcmmvqyw8wumn8ghj7mn0wd68ytnzd96xxmmfdejhytnnda3kjctvqqs0q693ptuuyxqe0xrw0376gxqdjquttkppzvwgks6whfrz929p6hqx7qg2x team (with pre-1.0 bdk) was doing some local storage but also persisting via https to an encrypted key/value store. You should also ask Dario what he's planning to do with `bdk-wasm`.
https://github.com/MetaMask/bdk-wasm