Landscape Table of Contents

Landscape TOC is trivially done in book fashion. The generated .toc file would have landscape pages and 3-column layout.

But this (in addition to lacking page number elements):

a. looks more like a BOM (Bill of Materials), or parts list, than a TOC, and
b. you apparently want it as a Bordered table.

Doing this as its own book component file, as a Table, might be the easiest thing to do. The table would flow across pages as needed. The various cells could be Xrefs elsewhere in the book, so auto-updated when pn/s and nomenclature evolves.