Set Stored Procedure parameter name as variable

Is there any way to set a stored procedure parameters name as input variables and not as fixed strings?

I'd like to pass @item().param_name as variable as follows:

I've seen a possible solution, that is passing through Dynamic Content of source settings the full json string with parameters configuration as follows:

@json(string({"Params":{"ParameterName1":{"value":"ParameterName1Value","type":"String"}}}))

@json(string(concat('{"Params":{"',variables('par_name'),'":{"value":"',variables('par_value'),'","type":"String"}}}')))

But I get this error:

Which is the json struct format that Dynamic Content needs?