In Canada, each province has its own public healthcare system and its own program to subsidize drug costs.
HIV treatment can be 100% covered or partially covered by the government, depending on the province. Provinces that do not offer full coverage to everyone usually ask for a patient contribution that is based on income. Also, if the person has supplemental health insurance (generally provided through employment benefits), some provinces may ask the private insurance company to pay for the treatment costs first, if they don't, then the government pays for it.
We also have public sexual health clinics and mental health clinics. PrEP is fully covered by some provinces and I believe PEP is covered almost everywhere.