Is it permissible for a man to wear a hairpiece (hair extensions) that is attached to the scalp with glue in areas where there is no hair or sparse hair after completely shaving it, and is the ablution valid with it, knowing that it allows water to reach the scalp except for the glued area?

It is not permissible for a man to attach human hair, whether from a living or deceased person. There is no difference in the ruling on hair extensions between men and women, except for the concession granted to women for the purpose of beautification when needed. Furthermore, a wig that is affixed to the head is prohibited, and it is not sufficient to wipe over it during ablution (wudu') or ritual bathing (ghusl). A man does not suffer from baldness as a deficiency, and he can cover his head.