Worth splitting the two things in the question, because the answer isn't the same for both.
For classic SEO, people have argued about unlinked mentions for years, and nobody outside Google can settle it. Google has patents on implied links, Bing has said co-occurrence matters, neither is confirmation that it's weighted today. Anyone telling you definitively either way is guessing.
Local is clearer. Citations are mostly unlinked mentions of a business name, address, and phone, and consistency across them is well established for local visibility. Plenty of directories publish listings with no link at all, and they still count.
AI search is more obvious because these systems read text. Nothing needs a hyperlink to associate your brand with a topic. Get mentioned in enough places in the same context, and that association exists whether anyone linked or not.
Probably marginal for rankings. Real for local. And increasingly, the thing that matters for AI visibility is a bit strange, when the unlinked mention used to be the consolation prize.