Got something to contribute: Here’s how to target specifically block reference embeds:
.internal-embed[src*="#^"]
For anyone who is interested wtf all those symbols mean — .internal-embed divs have a src attribute which has the link text in it (so if you’re linking to a block ref in a page called note, it would be src="note#^blockref".
The square bracket part is an attribute selector which checks if the src value contains (*=) #^ — which is how you tell it’s a block reference link.
If you wanted to target heading links, you want where the src contains # but not #^, so you’d have to use something like this:
.internal-embed[src*="#"]:not([src*="#^"])
For full page embeds, you want neither # or #^ so
.internal-embed:not([src*="#"]):not([src*="#^"])
As @Klaas pointed out in discord, this also means if you want to target embeds of a specific page, you could do
.internal-embed[src="The exact link I want"]