For Field Mapping operations (CSV import, later type conversion) add formula field for concatenating data

I find myself using both CSV import and Entity Conversion to other Databases frequently at the moment. One thing I think would be really useful to have for both (at least when Entity Conversion gets Field Mapping), would be some form of temporary Formula-driven field type that you can create as part of the Field Mapping. This field should have access to the CSV Field names being imported and be able to operate on them just like native Field Types. You would specify a destination field type (text, number, etc.), and the formula output would have to conform to that type, but unlike normal formula fields it would fully convert to a static (non-formula) field of that type after you import/convert. The point of it is basically to offer a more controllable, powerful way of dealing with fields that you want to bring in, but want to perform some operation on rather than use the data as-is, in separate fields. The most common would probably be some type of basic “concatenation”, but there would no doubt be other uses, and even with concatenation scenarios it would be much nicer to be able to do e.g.

<field name>: <field value>
<field name>: <field value>

OR if you prefer,
<field name>:<field value> | <field name>:<field value>, etc.
<field value> | <field value>, etc.
I.e. you can set the concatenation up in exactly the way you prefer.

This kind of feature would actually address a claimed original intent of the Entity Conversion that is not yet available:

Emphasis is mine.