Yeah, I kinda think the attempt to do this introduces more risk than it’s worth. *i tried this years ago on a failing clutch cable* and it very quickly made it worse. Off roading the Subaru (yes) got some water in the cable. I used a needle fitting on the grease gun to get me inside and allow me to force grease into the thing. It was a disaster in one week and I spent the $112 (1999 prices) for a new cable.
i have had sealed wheel bearings go bad, but my use preceded them. Towing heavy in endless mountains, the front hubs got so hot that the grease leaked out of them (never faded the brakes, but a witness told me my brakes were smoking for miles). But they didn’t fail for the rest of the time I had in that truck. one of the rear bearings was destroyed in that trip (also sealed bearing). The axle was so hot, you could feel the heat coming off of it simply walking by it in shorts. I have no idea the axle temp, but it starting making noise within days, that eventually ended up getting so very bad, and then replaced.