not yet afaik, that's an nsecbunker feature though. I would love to see support for that added to, including in more clients. I should be able to give a website on the desktop my public key and when it wants me to sign a message with my *private* key, it asks the client I use on my phone, which then prompts me to approve the signature request. In the background the two devices can talk over nostr to share the signature requests and signature approvals and such.