Keychat uses the OS WebView for it's browser. The Android OS webview is Chromium based.
https://github.com/keychat-io/keychat-app/blob/main/packages/app/lib/page/browser/WebviewTab.dart
nostr:npub1h0uj825jgcr9lzxyp37ehasuenq070707pj63je07n8mkcsg3u0qnsrwx8 does this nicely. Not sure what browser engine it uses under the hood?
Outside of that, Amber bunker works nicely too.
Discussion
On GrapheneOS, webview is Vanadium browser based. No invasive Google spyware.
Unlike on desktop, where the Nostr ID is a browser extension, in Keychat, the browser (WebView) is an extension of the ID and BTC wallet.
Vanadium is Chromium based but with a lot of security and privacy changes. Because Vanadium is also the OS WebView you can run apps using WebView in a safer fashion, they benefit from such features:
https://grapheneos.org/features#vanadium
Also a control for WebView JIT per app to reduce a large JS JIT attack surface for them. Our PDF viewer is an example of a WebView app.