> I wish this was available for legal texts, making it easy to jump from one law to the referenced next legal provision. Many legal provisions, especially in very regulated areas, make use of “functions” “imported” from other, totally different laws.

I mean, it "is", to the extent that if you put in the work of hyperlinking all the things during the digitizing process they can be.

Légifrance is fairly highly (though nowhere near completely) hyperlinked for instance, here's one of the laws I selected from the front page: https://www.legifrance.gouv.fr/jorf/id/JORFTEXT000044446848

Many (though nowhere near all) the legal texts being referenced, modified, or inserted (as references, into other texts) are hyperlinked.