I made a service to store arbitrary files as URLs that is similar. The hard part is files that are too large, I can handle files up to 5mb if you click on them all via local storage. Compression helps a lot as making them base64 increases the size quite a bit.
Yes, I did this for self-contained reports in maybe 2014. All images referenced (containing diagrams) were embedded as data URIs. Restrictions are AFAIK more picky now, though so YMMV in 2021.
https://podje.li