Does V3 handle a customerquery by displayname? For now I know I can do a service call with findbyid() but I would like to do a customerquery by the displayname.
Yes. It is supported.
Query - select * from Customer where DisplayName='John Doe'
Ref Customer Entity Doc - https://developer.intuit.com/docs/0025_quickbooksapi/0050_data_services/030_entity_services_reference/customer
DevkitRef - https://developer.intuit.com/docs/0025_quickbooksapi/0055_devkits/0150_ipp_.net_devkit_3.0/query_filters
You can try this call using ApiExplorer. https://developer.intuit.com/apiexplorer?apiname=V3QBO
Thanks