moving all the params from url to code, we can make it to 326 bytes
data:text/html;base64,PHNjcmlwdD5zPW5ldyBXZWJTb2NrZXQoIndzczovL25vcy5sb2wiKSxzLm9ub3Blbj0oKT0+e3Muc2VuZCgnWyJSRVEiLCJxIix7ImlkcyI6WyI4MjA0ZTkyYWRlMTgxYTI0YWIwMjA2MTQ0ZmU1YzBiZjU1MWUxOTQyODEwZjk4YmJiNmMwZjI5NDYyODY5OWZkIl19XScpfSxzLm9ubWVzc2FnZT1lPT57ZG9jdW1lbnQud3JpdGUoSlNPTi5wYXJzZShlLmRhdGEpWzJdLmNvbnRlbnQpfTwvc2NyaXB0Pgo=
it seems base64 encoding in data uri is not necessary
this is just 257 bytes
data:text/html;nos.lol,
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249 bytes
data:text/html,
and now we have additional benefit that the note id and relay url are in clear text, can be configured in url again