We really should standardize on a solution for this. I actually was just working on something similar, an embeddable `nfile` entity. This fails the naive fallback test, but I don't like that nip 54 prioritizes one url in particular. This way we don't need a full event too, just a data structure that can add blurhash etc as needed.
nostr:nevent1qqswc3dr5zwqh6dn9m5pgruy90y40atd9dl4q8ajy8rckmhun7g9u5spz4mhxue69uhhyetvv9ujuerpd46hxtnfduhsz9rhwden5te0wfjkcctev93xcefwdaexwtcpzdmhxue69uhk7enxvd5xz6tw9ec82c30qyvhwumn8ghj7un9d3shjtnndehhyapwwdhkx6tpdshsz8rhwden5te0vf6kx6m9wshxxmmjv93kcefwwdhkx6tpdshszrnhwden5te0dehhxtnvdakz7qgnwaehxw309ac82unsd3jhqct89ejhxtcpr3mhxue69uhkx6rjd9ehgurfd3kzumn0wd68yvfwvdhk6tcpzemhxue69uhhyetvv9ujumt0wd68ytnsw43z7qgjwaehxw309ac82unsd3jhqct89ejhxwvcy34