Is it permissible for a wife to ask her husband to use medications or devices to enlarge his penis, or to attach a prosthetic penis to his own for her enjoyment in the first place?

There is no objection to the husband consulting doctors to prescribe medication for penile enlargement, or using a condom and the like, if that completes the pleasure for his wife, provided there is no harm. This is to achieve good companionship and to keep the wife chaste. As for the phrase "there is no shyness in religion," it is more appropriate and correct to say, "Indeed, Allah is not ashamed of the truth."