hi, dev building Shaper here. Both, Shaper and Metabase, can be used to build dashboards for business intelligence functionality and embedded analytics. But the use cases are different: Metabase is feature-rich and has lots of functionality for self-serve that allows non-technical users to easily build their own dashboards and drill down as they please. With Shaper you define everything as code in SQL. It's much more minimal in terms of what you can configure, but if you like the SQL-based approach it can be pretty productive to treat dashboards as code.
sorry, so it ain't an alternative in any way. Its like saying a bicycle is an alternative to an airplane, both have seats...