To be honest, would a spreadsheet not be a good use for this? There are FOSS asset trackers, but a simple .ods with a pictures column might serve you well.
Are there additional features/conveniences you are looking for?
Yeah, I just have an Excel spreadsheet. Item, model, serial, purchase date, purchase value, order number so I can find it in my email if applicable. The only thing I've filled a claim for was when my bike got stolen (purchased $500, reimbursed $2400 because apparently they changed to high end bikes) and they didn't ask for any records.
I'd also recommend a video walkaround of your house at least once a year.
I wonder if something like a picture or video is sufficient to inventory quantities and general cost, such as clothes. The number of t-shirts I have changed over time, but a week worth of Carhartt adds up
I was thinking of doing that, but I don't think it would handle attachments gracefully. I also don't want to inflate it to a 100gb document with all of the attachments.