How do you track a large inventory of original artwork in Excel without it getting out of hand?

Sitting here cataloguing about four years worth of botanical illustrations and I finally hit the wall where my spreadsheet is just not keeping up anymore. Right now I have columns for title, medium, size, date finished, whether it's sold or available, and a few notes fields. Simple enough at first but it's grown into something with 300 plus rows and I keep wanting to slice it in ways the current layout doesn't support well.

The thing tripping me up is commissions. A commissioned piece has a client name, a deposit date, a delivery date, and sometimes revision rounds, which is a totally different shape from a piece I just made for myself and listed in a shop. Cramming both into the same table feels wrong but splitting them into separate sheets means my availability overview breaks

Someone suggested a lookup column that flags the row type and then using SUMIFS or XLOOKUP to pull things into a dashboard sheet, but I've never built anything quite like that and I'm not sure if it's cleaner than just tolerating two separate tables

What's the right way to structure source data when the records don't all have the same fields? One flat table with blanks where something doesn't apply, separate tables, or something else entirely?