What I don’t bother with anymore, that an app on my phone has definitely replaced, is an altimeter watch. In the old days an altimeter was occasionally useful, especially in cloud cover. Now, if I need to, just quickly check exact positions on my phone app.
Must admit, when in the proper thick of it (Scottish winter, alps etc), I welcome the new easy option stuff to assist, but equally mourn the passing of slight chaos, fun and satisfaction when you nav’d out of a pickle using various compass skills, pacing, attack points, aiming off, aspect of slope, questionable altimeter reading etc, of old. Now replaced with a quick check of a phone app/GPS.