Hello, I've been doing some research about how can I access the __PC sufix in a LWC but the short answer is: there's no way to do that. In order to work with person account fields, it is required to import the field from the contact.
@import PA_Field from '@salesforce/schema/Contact/Your_Custom_Field__c'; then you may reference that field in the js controller
paField = 'Account.field_pc';
I think it would be easier for developers to access directly to the __pc account field rather than going to contact and then doing the reference to the contact field.