Is a ring with an attached nail—which can be opened during ablution or eating—considered a forbidden extension, knowing that it is not glued but worn like a ring?

The use of artificial nails for beautification is forbidden because it involves harm, imitation of animals, deviation from the natural disposition (fitra), and it prevents the validity of ablution (wudu'). However, their use for treatment is permissible. As for the nail ring, there is no harm in wearing it if the nail is not long and if it can be removed for ablution.