Can an application have 2 databases?

Can one application have multiple databases?

so, based on user login, the application should connect different database server. For Ex: if user "xxx" login with credential and belogs to "ABC" company and the database is "ABC", then ABC data need to display on the web page.

Can we connect 2 database in Web application?

Yes, but you will have to manage each app very carefully, creating a seperate directory for each app in Firebase Database and Storage.

Can a project have multiple databases?

Generally, if one project consumes multiple databases, it is because it must consume different, often legacy sources of information that originated outside of this particular project. This is most common in Enterprise environments.