Zero connection between clutch and transmission a possibility, more below, but more likely zero connection between shift lever/linkage and transmission.
Had something similar happen in my Turbo. Went to shift and suddenly the lever had less resistance. I can't be certain now but the lever might have felt a bit loose.
After I had the car flat bedded to dealer tech found one of the cables to the transmission linkage loose. A ball socket at the end of a cable had failed and the ball had come out of the socket.
My advice would be to check the shift lever to transmission linkage very carefully for a broken/loose cable.
With the engine off have someone work the lever from gear to gear and observe the linkage moves and so too do the levers on the transmission. I do not expect any real difficultly in doing this but if for some reason the gear engagement feels like there is some resistance do not force the lever. This suggests there could be something wrong inside the transmission.
If the linkage appears intact and functional then an explanation is the clutch disc is not making contact with the flywheel/pressure plate. The old zero connection between the clutch and transmission. This can be due to a bad release bearing or the pressure plate spring has lost its spring.
At the same time have the helper press then release the clutch pedal to at least ensure the slave is moving the arm that moves pressure plate away from the disc.
You want to be sure you eliminate other possible explanations before you go to the trouble of dropping the transmission.