On page 179 of the Rogue Trader core rulebook, i the box labeled 'Are Navigators Psykers?' it says:

"Navigators are not marked as psykers in the traditional sense within the Imperium, though they do have a connection with the warp and use its power to fuel their abilities. For all game purposes, however, a Navigator character is considered a psyker. This means that weapons, powers, and creatures that have special effects on a character that is a psyker will have similar effects on a Navigator character."

Does that mean Force weapons can be used by Navigators in a similar manner to Psykers?

If I do remember well, the Force weapons section in Into the Storm does tell that Nabigators can't use them like a psyker...
yep. p128 of Into the storm, the Force weapon quality sidebar, last paragraph.
"Although Navigators are considered psykers, their powers are different from a regular psyker and they do not gain
any of the above benefits for using a force weapon."

Thank you!