What I’d like to see, and I’m probably the only one, is support for data:// URIs, paired with SVG support.
An SVG image can be quite small and yet vibrant. It would be possible to URL-encode or base64 encode a small SVG file and cram it directly into a Nostr note by way of a data:// URI.
Or even gzip+base64 SVG in a data:// URI.