yeah, i want this too
it's not hard to write one... as it is i already wrote the code for selecting all events either authored by one or more pubkeys or mentioning one for export over an administrative http port on my relay, but i still have to finish debugging its binary codec, which is a bit broken still
it probably wouldn't be hard for me to move that code into a place so if you are authed and you request a filter that is just your npub in author and/or only in a p tag that it just sends the whole shebang to you, no limits, simply need a client that can comprehend this capability and put it somewhere... something like that ... what is it... some android relay-in-the-phone thing... named after some rock or something