I think there are plenty of channels that aren’t just using “cheap stock photos and/or blender animations”, and I can list some examples if you’d like. The first criterion is harder, though, because sci-com by its very nature isn’t going to be original research, so channels in this category tend to be more creative or opinion-based (i.e. multi-hour video essays).
That said, if I’m trying to really get at the gist of what you’re saying, I think you’re looking for shows that have a lot of original work and high production value?
Some random examples I can think of (I’m sure there’s plenty more):
- 3 Blue 1 Brown
- Captain Disillusion
- Gamers Nexus (specifically their investigations)
- Smarter Every Day
- Every Frame a Painting (inactive but with a huge catalogue)
- PBS Eons
- Technology Connections
- Montemayor
- Taylor Lorenz
- Climate Town
- Tantacrul
(this is excluding so many great video essayists and artists since the original comment seems not to be referring to those)
I think they intend to use one for voiced “th” and another for unvoiced, but they mess up a few times