Had the same exact problem for years with a non-Volvo. Ended up fixing it by replacing the brake calipers And rotors. at some point pads had worn down enough to damage calipers but nobody noticed the calpier damage for years. At the same time replaced tires for symmetry and balanced it all out. Not cheap but very solid ride after that. Maybe this is your problem as well.
pretty amazing how much vibration can come from bad brakes.
pretty amazing how much vibration can come from bad brakes.