This reminds me of https://www.youtube.com/watch?v=Nz8ssH7LiB0. Transforming all data to a string/nvarchar is like putting all of the shapes in the square hole.
This might be ‘good enough’ if you have a simple use case, but I wouldn’t recommended doing it like this in more complex situations. It can mess up the data that you had.
For true data type consistency, keep the database columns as you defined them, find out which columns didn’t have the correct data type and convert the data in there carefully. Put the shapes in the right hole!