HubSpot makes it tricky to do calculated percentages like % Gross Profit when you’re working with Line Items. So I totally hear you and it seems like you’ve been given a lot of options.
If you go the spreadsheet route, you can get a lot out of leveraging Coefficient’s, certified 2-way sync between HubSpot and Sheets or Excel on HubSpot’s marketplace.
You can pull HubSpot deal and line item data into your spreadsheet, then calculate metrics like % GP there. It’s much easier to do the math (like Margin ÷ Revenue × 100), group by month, etc.
Then, you can either 1) push the calculated data back to HubSpot to build your report there, or 2) just build your visualization in Sheets and embed it back into your HubSpot dashboard. I made a quick video on how this works.