Okay, did some reading.
Pact of the Tome CAN give you the Find Familiar ritual spell, but you wouldn't start with it. You have get an invocation to boost it.
You can also take a feat that gives you access to ritual magic, though to get Find Familiar you'd have to take the feat to gain Wizard spells, which means your rituals would be based on your Intelligence, not Charisma.
Plus, as a feat, you could only start with it if you were human.
Pact of the Tome CAN give you the Find Familiar ritual spell, but you wouldn't start with it. You have get an invocation to boost it.
You can also take a feat that gives you access to ritual magic, though to get Find Familiar you'd have to take the feat to gain Wizard spells, which means your rituals would be based on your Intelligence, not Charisma.
Plus, as a feat, you could only start with it if you were human.