Picked up a decent rider bianchi piaggio, that has a clip on the middle of its suzue hub, When you slide it over theres a hole in the hub. What its purpose, its to small for grease? Thanks

My LBS guru told me to ignore it.
He said it originated on Italian hubs and besides thick lube for a short race he told me to serivice the bearings the standard way.
Whether this is true or not I have no idea. But I listened to him.

You can dribble a little oil in it and then hold your wheel at a 45 to the side and give it a spin. The oil will rejuvenate older grease to a degree. It really is a throwback to the days when the roads were gravel/dirt and the bearings/hubs didn't have any seals to speak of.

And they scratch the hubs when you slide them to the side.