How to link different databases? We are a company doing surveys with different kind of questionnaires. There is a company in Mumbai (MySQL) specialized in Type 1 questionnaire and one in Peru (SQL-Server) specialized in Type 2. I also work with a CRM system as Salesforce and want to connect these data as well.

I thought about getting all these data into one in-house database using ETL. I was curious if it is possible to virtually connect these data warehouses so I do not need a DW in-house and can query the data where they are stored but can connect to them. Is this possible? I could not find anything but maybe I am looking with the wrong vocabulary.
If this were me, I'd use SSIS and import everything into a DW locally. Then you can do whatever you want/need with minimal impact to all of those remote systems.