Different tongues would definitely be interesting.
There's a couple routes you could go in that regards.
First, just plain tongues, with no mouth, or, if there is a "mouth" it's just decorative, to distingish it as a tongue, rather than a phallus.
Second, you could design "oral fleshlights" with the tongue sticking out of the mouth.

Another thing I thought of is dildo designs that have scrotums, kind of like is the case with this this horse dildo.
An OC I'm in the middle of designing has a knotted penis, very much like your Arctic Fox model, but, she (a herm), also has a "Scrotal Tunnel" piercing, in which increasingly large gauges are inserted in the scrotal tissue until, in theory, it is large enough to allow something such as another character's penis to pass directly through the scrotum between the testis. (Caution, Photo of a real Scrotal Tunnel)

Hi and thanks for your answer!

I also asked this question on my discord server, and it seems indeed that most of you want languages. So I'll probably go with my first idea for the next one.
I've also heard a lot about penetrable, but I'm not really interested in those. Indeed, they have more of an "industrial" function than an artistic one and are therefore more difficult to design. However, the idea of making one with a tongue coming out of it can be a good idea! It would make it multifunctional in a way.

As for the scrotum, it's clear that I don't carve enough of it. It's even something I avoided in my early days because it was tedious to do with my meager skills. I still made a few (like equus caballus or little pleasure). Today, I am more in the mood to make them.
I didn't know the principle of the hole in the scrotum. I doubt I will ever do one because it doesn't really attract me, but I thank you for teaching me something !