So, here's the thing, I would love to use something like this. This is an area I've been trying to address with various spreadsheets for years along with crudely drawn floorplans. The biggest issue for me, is that whatever solution I go with, MUST export to an editable spreadsheet format (export to XLSX preferred).

For me, this is the type of information I want to export to multiple storage places for backup, and keep a printed copy in my fire safe. Not just in a SaaS. I'm perfectly fine paying for a SaaS service (if reasonably priced, no more than $5/mo for an individual), but I need these export options or I'd never sign up. Holding my data hostage is a non-starter.