This is a great initiative!
Recently we’ve had a good discussion on scientific workflows with Zotero.
I think the technically superior approach would be to approach the Zotero devs and ask for a local API exposing most of the functionality over a local web interface. Then Logseq could easily fetch the currently selected item, search, or add links back to any Logseq page citing an item. In principle this capability mostly exists through the debug bridge, but this is not officially supported, so I would not rely on it.
There is currently an ongoing discussion about integrating a local endpoint.
Less coupling and less features (no back annotation into Zotero) via automatic BetterBibtex export. Maybe the owner would be willing to also dump the zotero item-ids and attachment ids into the .bib file. With this information, Logseq could easily link back to Zotero with zotero://select links, but one couldn’t add links to Zotero linking back to the referenced pages.