I'd highly recommend the Kimball books, e.g. "The Data Warehouse Toolkit".

Unless you're working with a lot of data, the technical parts of a data warehouse are relatively easy to grasp (the dbt team wrote some great posts on how they structure their projects [1]). After that, what really makes a difference is how you structure our data warehouse, how you model your data in a way that allow you to query it efficiently and ask many questions. That's where the Kimball books shine.

[1] https://community.snowflake.com/s/article/Use-Case-How-We-Co...

Technical skills with databases are a must. It's basically a database engineer + being able to generate accurate and insightful reports/metrics/visualizations.

More value comes from database engineer skills as well as being able to understand the structure of a business. Little actually comes from the BI platform you choose.

If you're already doing engineering work you may be able to just go get a job focusing on data - if you're upfront about wanting to learn. I've found most people have learned the skills on the job. Besides the books mentioned I commonly recommend these resources

DataCamp.com has some great courses

Tableau has some great online education - many people learned BI from them

Many free resources for getting started with data at different levels (note: this is one of my sites) https://dataschool.com

Description of common roles in BI/data: https://chartio.com/learn/data-analytics/distinguishing-data...

If you can setup data pipelines and pump data into dashboards, the rest is just getting the business to ask the right questions.