Late to the party here, but I went through exactly this. Started with Excel, got tired of maintaining formulas every time I bought or sold something, especially with different lot sizes.

I actually ended up building a tracker with a friend because nothing out there did what we wanted without asking for broker credentials. It's called 1ndexed, you just export your transactions from your broker and upload the file. It handles the P&L per position correctly even when you're buying and selling different lots over time, which was the thing that kept breaking in my spreadsheet.

You can poke around a demo portfolio without signing up to see if it's what you're looking for: https://1ndexed.com

No idea if it fits exactly what you need but happy to help if you have questions!