Pharmacies play several roles in PrEP services. Pharmacists store and dispense medications, provide counseling, help with retention and adherence, and so much more.
In some places, pharmacies lead the provision of PrEP services.
from https://www.krrph.com
An early example is the Kelley-Ross One-Step PrEP service in Seattle, Washington. In that setting, pharmacists oversee all aspects of the PrEP service, including screening, HIV testing, other lab testing, prescription management, dispensation, counseling. There is a medical clinic upstairs, that provides advice and backup if issues requiring clinical management occur.
There is a video interview with the Kelley Ross PrEP service directors.