loading="lazy" is for images that are NOT embedded in the same file. So we either have entire site in a single HTML file or we have scalability for large stes. There's no solution that gives us both.
But if you just want to be able to save the entire website with Ctrl + S, then it works fine.
As an aside, loading="lazy" is the way in which images are embedded in the website from TFA https://i.imgur.com/wIkaE5g.png which was the reason why I mentioned it, although it certainly does not fit all possible use cases.