Patlatus

public class MD {
	public static String buildPackageXMLForMD(SObjectType mdt, String whereClause){
        String mdtName = [ select DeveloperName FROM EntityDefinition where QualifiedAPIName = :mdt.getDescribe().getName() ].DeveloperName;
        
        List<SObject> records = Database.query('SELECT DeveloperName FROM ' + mdt + whereClause );
        List<String> items = new List<String>();
        for (SObject r: records) {
            items.add( mdtName + '.' + r.get( 'DeveloperName' )  );
        }
        return '    <types>\r\n        <members>' + String.join( items, '</members>\r\n        <members>' ) + '</members>\r\n        <name>CustomMetadata</name>\r\n    </types>';

Patlatus

SELECT ParentId FROM FieldPermissions WHERE
Field = 'CustomObject__c.CustomField__c'
AND SObjectType = 'CustomObject__c'
AND PermissionsRead = true
AND ParentId IN (SELECT PermissionSetId from PermissionSetAssignment WHERE AssigneeId = '005USerID0000AAA')