Hello there TS1940, I've spend quite a while researching this niche on my own. Before running into search engine optimisation I used to handle handyman and cleaning jobs and i was really impressed how simple property inventories seemed to be, BUT.
When I started to dig in deeper, I realized it does not pay as good as it might seem, plus competition is a killer. The landlord-tenant-housing niche is crazy and if you lack good connections you'll have hard time finding landlords to work with. You should really, really research all the pros and cons of property inventories, before you bet your tenancy rent on it.