At least in the classes I’m taking as a beginner there is a bigger focus on active following compared to some of the other dances I do.
There is no consensus on what active following is when discussing it in written like here.
It is good if active following is indeed taught from beginner levels. In my experience with actual dancing, WCS has most active following amongst the social dances I have done. I don’t know how much it is taught in WCS just like I don’t know how much is taught in Tango. I have seen a few individual instructors in each teaching it without calling it active following. The question is are you extrapolating based on an instructor or two teaching so.
A distinction should also be drawn between teaching good dancing and active following. Good dancing can be about good following or good leading, but more of good following in this case.
In the sense of suggesting musicality, adding little bits of resistance,
Depends on what you mean by adding resistance and how it is added. Good dancing/following requires creating a bit of resistance to improve connection. That is not active following.
Resisting to follow what is led is disruptive and not active following either. It is like a car having two drivers at the same time.
Technically to me active following is - following the lead that is given and then doing something interesting with the given lead. A good leading is inviting a follower and then following the follower to finish the movement. Most good leads always follow the follower. This way as a leader you are neither rushing the follower nor slowing them down or throwing them off balance.
taking over parts of the giro,
Again I am not sure what you mean by taking over part of giro. I have discussed this with many instructors. The consensus is that unless follower has right technique and timing, there is not a lot a leader can do. Someone could argue that a leader can lead the giro timing (and technique) with clear assertive lead. But that only works with some followers, not all.
Not everything can be led, if a follower lacks technique and ability to be balanced. Technique can include ability to disassociate. As a leader I have to adjust and compensate if follower can’t disassociate sufficiently.
adding adornos to prompt lyrical dancing, etc
This is certainly not active following. Also adornos should not interfere with dancing. There is space and time within which a good dancer adds adornos. A good leader will also wait for follower to finish the adornos. A good follower can also add adornos between the movements without the leader being aware of it. I haven’t seen any class devoted only to how and when to use adornos.
As to lyrical dancing, they can also be used in rhythmic dancing.
You can create your own adornos.
This might sound obvious to most experienced dancers but for me as a lead is like having the instruments explained so I can listen to them better in the dance.
Since you danced salsa, it is common in salsa beginning classes to teach or inform students to isolate particular instruments. There are a lot more instruments in salsa music. Some are rhythmic and some melodic. A few like piano can do both.