Is it possible to expose custom table data to Views without custom code?
Apparently Views Custom Table does that:

View custom table module provide you functionality to integrate your
custom table data to views, and access all it's column in views. This
module use hook_view_data to add custom tables in views. this module
provides you following functionalities.

Auto integrate custom table data to views
Auto map mysql data types with drual data types
Extend relationship of custom table data to drupal entities