"DataSet does not support System.Nullable" while assigning a nullable datatype to a table column

I need to put empty values in some column of my DataTable. Empty values does not mean DBNull values but strict nulls. So, for this purpose I assign column's datatype as follows:
myTable.Columns.Add("MyCol", typeof(decimal?));
But the compiler says "DataSet does not support System.Nullable<>".

Is there any way around this? I don't want to substitute zeroes for nulls while inserting values in the table, like this:
myRow["MyCol"] = val == null ? 0m : val;
because it makes a difference in my program whether inserted value has been null or not. I also cannot substitute DBNulls for nulls while inserting values, like this:
myRow["MyCol"] = val == null ? DBNull.Value : (decimal?)val;
because compiler says "error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DBNull' and 'decimal?'

I googled for this issue and found just two similar cases:
https://bytes.com/topic/c-sharp/answers/514233-adding-nullable-datetime-column-datatable-does-not-work
https://www.tek-tips.com/viewthread.cfm?qid=1542262
Both, however, do not have a solution that would work for me.

So, the only option I could invent was NOT assigning the value when it is null:

if (val != null) myRow["MyCol"] = val;

Is this the only way? And is there really no way to make DataSet support System.Nullable, so that code
myTable.Columns.Add("MyCol", typeof(decimal?));
be valid?

Thanks to JHBonarius, I got the main idea from one of those answers: Define a column as nullable in System.Data.DataTable The idea is to cast everything to object. First of all, there is no need to set table column's AllowDBNull property to true, since it is true by default. Second, I stuck with the line of code myRow["MyCol"] = val == null ? DBNull.Value : (decimal?)val; because of compiler error CS0173. The solution here is to cast both parts to object, like this: myRow["MyCol"] = val == null ? (object)DBNull.Value : (object)val This works without error, and DBNull value is inserted in the table column. That's it.