I am gonna dissect something so emotional like kissing to the technical details
Some women don‘t kiss back so no big loss and on the other hand some dolls really feel like they are kissing back - imagination and emotion.
As Mr.K already said the harder silicone heads, although very realistic to look at, are rather hard and mostly have a closed mouth, so no cavity.
Then there are softer silicone heads - Sanhui is a good example - much softer, a nice mouth and obviously built for sex, so only a removable tongue.
I really love my Piper doll, mouth closed but a really soft silicone and very kissable at least for me, but that‘s purely emotionally subjective.
I‘ve seen Elsa Babe offers a fixed tongue, but I don‘t have any experience.
That was all about silicone heads that I can offer. TPE others may chime in.
By the way
here
Jo