Metabase is great! I was using it 4 - 5 years ago and it was shocking how good it was as OSS.

It depends on your use case: Metabase is designed for BI (i.e. reading large amounts of data and chating it); Retool is designed for apps that write back to databases / APIs. Metabase (TBH) is better at charting (they have nicer charts, better caching, etc.). But it doesn't support writing back to APIs or databases. For example, if somebody on your team is asking "what was our revenue last month", Metabase is going to be better for that. But if your team wants an app that "shows possibly fraudulent orders, with a button to cancel & refund them", Retool is better for that (and Metabase wouldn't allow you to do that).