SQLite DB Size Column Data Type Considerations

I'm working with an SQLite DB where all columns are of NVARCHAR data type.

Coming from MS SQL background I know that NVARCHAR has additional baggage associated with it, my first impulse is to refactor most column types to have concrete string lengths enforced (most are under 50 chars long).

But at the same time I know that SQLite treats things a bit differently.

So my question is should I change/refactor the column types? And by doing so is there anything to gain in terms of disk space or performance in SQLite?

DB runs on Android/iOS devices.

Thanks!