A few more resource pages to share.

Rule34hentai model release tag: https://rule34hentai.net/post/list/model_release/1

Pixiv Model release tag:
https://www.pixiv.net/en/tags/model_release/artworks

Mostly SFM stuff on both and requires an account to see some content on both sites.

Internet Archive:
https://archive.org/search?query=subject%3A%223D%22+nsfw

Hard to find useful models, but there's a few here and there, it also contains archived versions of tutorials from playlists shared on the OP post.

Renderotica's Gore catalog: https://www.renderotica.com/Store/cat/11086_Explicit-Content-(Death-or-Dismemberment)
Sadly paywalled, and most of the content is for DAZ studio, but DAZ can be (relatively) easily imported to Blender. You can find some free models and resources, mostly original content as opossoed to smutbase, but most models look like shit.

Turbosquid:
https://www.turbosquid.com/Search/3D-Models/free/rigged/blend
Another huge library of 3D resources for Blender, Maya, Etc. Sadly most of them are also paywalled.

Other 3D resources sites:
https://free3d.com/
https://www.blendswap.com/
http://www.makehumancommunity.org/ Tutorial: https://www.youtube.com/watch?v=a6Jd6rBDk-0