A little while ago I tinkered with data URLs to carry a small 80's home computer program directly in the emulator URL, it worked well apart from the fact that the "payload" is limited to around 1.5 KBytes.

The navbar in browsers may accept more (up to 4KByte in my experiments), but other 'infrastructure' where the URL needs to travel through (for instance URL shorteners) may clamp the source URL to a much shorter length.

It would have been awesome to distribute ready-to-play emulator links for home computer scene demos without hosting the data anywhere, alas it didn't work except for very small demos :)