Why is it so difficult to find an insertable packer?

My wife likes to insert the balls of a small packer into her vagina, and she tells me to suck her dick for lite roll playing. She likes it small because I have to get close while sucking it, but we’relooking for a packer that is short and the balls on the outside, but nobody makes one that is insertable like the strapless strap- on dildo. The only issue with those is that they’re not realistic and we really want one that’s under 4”, soft and good for oral.

If you know where I can buy one or have it made custom, I would greatly appreciate your suggestions!