Could ac not blowing cold be caused by low refrigerant?

Most common cause. Refrigerant leaks slowly over years and needs a recharge.

Could ac not blowing cold be caused by failed ac compressor?

If the compressor doesn't engage when you turn AC on, it has failed or its clutch has failed.

Restricts airflow, making the AC seem weak even if it's cold at the vent.

Weak airflow at all settings means the blower itself is failing.

Damaged from road debris (in front of the radiator) — leaks refrigerant.

Severity is rated Low. Start by replacing the cabin air filter (cheapest). If still weak, an AC recharge with leak detector dye costs $30-50.

AC problems range from a simple recharge to compressor failure.

Severity: Low

Start by replacing the cabin air filter (cheapest). If still weak, an AC recharge with leak detector dye costs $30-50.

Low refrigerant: Most common cause. Refrigerant leaks slowly over years and needs a recharge. Shop ac refrigerant
Failed AC compressor: If the compressor doesn't engage when you turn AC on, it has failed or its clutch has failed. Shop ac compressor
Clogged cabin air filter: Restricts airflow, making the AC seem weak even if it's cold at the vent. Shop cabin air filter
Bad blower motor: Weak airflow at all settings means the blower itself is failing. Shop blower motor
Faulty AC condenser: Damaged from road debris (in front of the radiator) — leaks refrigerant. Shop ac condenser