Almost all of these are pretty nice. I disagree with the preview-on-hover though. That sends off a request to a possibly unknown (possibly unwanted) destination. I often hover a link to look at what the URL popup says in the bottom corner, before following it. It's just not a very privacy-conscious feature, even if convenient.
With modern Content Security Policy restrictions and such most sites now have, previews almost entirely have to be implemented server side to make them work anyway, so no real privacy fears.
For some use cases (eg editing Wikipedia, so being able to see if something linked is a stub or not say) its useful, but not i think in general for external sites.
I've seen link preview solutions start to appear that I would assume are doing some basic moderation and logic to ensure consistency. I've recently seen on product hunt - Linkz.ai link previews SaaS .
