@dani2 So, I've done this a bit in the past - I ended up using a PowerApp to do what I was initially using a flow to do (I found my users were not batching updates - they were doing individual updates and wanted to be able to add other data at the same time - so it's not the exact same that you're doing).
I think you need to break it down into 2 steps - the Power BI visual essentially passes the data to the Power Automate flow - so you don't need the SharePoint columns at that point - you just need to make sure you pass all of the appropriate data to the flow - any field that you'd want to add or update in your SharePoint list. Once you do that, you can head to the flow.
From the flow, you'll be able to see the columns you passed through from Power BI and that's where you'll map those fields to the SharePoint columns and add items or iterate over the existing rows in SharePoint if you're updating data. That part can be complicated because you're looking up rows in SharePoint based on what PowerBI fed the flow but it's possible.
There aren't great videos for your specific use case but here's a good one that looks at the Power BI data coming into a flow and how to manipulate it (in the video it's about generating and sending an email - SharePoint will be a bit more complex): https://youtu.be/KtKJGZArq9w
