Which product is best for me?

[cwalker7]

I am wanting to connect my data to a BI Dashboard, like Tableau, Power BI, and Looker Studio. I have two data sources that I am wanting to connect or create a relationship between. I have mail data and sales data. My mailing data is in an excel sheet and I update it once a week because we send mail out once a week. There are around 1.3 million rows of mail data separated into two sheets within the same Excel Workbook. The Sales data is being POST from our CRM's API onto a Google Sheet, using a third party Google Sheet API connector. 

As of now, I am just copying and pasting the Sales data from Google Sheets to the Excel workbook that contains all of the mail data. Each piece of mail has a unique "response code" that is also in the sales data, so there will be a matching response code in the mail data for every sale we have. The mail data contains more metrics than our sales data and that's why we are wanting to create a relationship between them. As of now, I am using the VSTACK function within Excel to return the full rows of mail data that have a matachin "response code" with sales onto a new sheet.

I feel as if using BIgQuery, Cloud SQL, Cloud Spanner, Bigtable, and/ or API Manager could make the process much more efficient. But not sure which one fits my situation best.

The main thing I would like to achieve is to create a relationship between the two sources (mail and sales) through a relational database, and then create a live connection to a BI Dashboard to analyze this data. I don't know much about coding or computer languages though. So if that isn't an option because of my lack of JSON knowledge, then I would like to at least connect the CRM's API directly to the BI instead of using Google Sheets as a middle man. 

I am very willing to learn about these databases, but want to make sure I am utilizing the right product/ products before attempting. I just want to create a live connection with the data sources and a BI dashboard, instead of having to manually copying and pasting daily. It seems like creating a relational database is a great option, but if not I at least want to create a live connection and then create a relationship within the BI Dashboard. 

Can anybody give me some guidance? Thanks so much!