Raindrop.io full text search should work but only in the paid pro plan. And even then, I think the problem with the example you cited is that “comments” are gen

Raindrop.io full text search should work but only in the paid pro plan. And even then, I think the problem with the example you cited is that “comments” are generally stripped off (like they are in “reader mode” apps) so that HN replies are not indexed. I always recommend Zotero as a local/online bookmark manager. It does full text search, but you have to "save page as snapshot" and set search to "everything", for it to work