You don’t NEED accelerometers to figure out latitude or true north.
The gyros provide a star-fixed reference system. This will appear to be spinning at about 15 deg/s relative to your aircraft due to the earths rotation. And, here is the good bit: The axis of rotation relative to your aircraft will be parallel to the rotational axis of the earth. Alas, it (or its projection in the horizontal plane, if you wish) points to true north.
The angular difference between this axis of relative rotation and its projection in the horizontal plane is your latitude (at least on a perfectly spherical planet, otherwise corrections might be required).
Yeah, that contained a bit of reiteration.
Cheers,
Fred