Yes, i am. While my teachers don't use the term step projection i see some relation with what opendoor outlined in the OP and the video and what they teach. On the other hand i have never heard about leading with feet before, and i am puzzled how it is supposed to work. (when i took classes with el pulpo he was big on thinking about using the thighs as leading surface when doing his style of enganches, but that was only a specialized application of leading with the legs for special circumstances). As you are familiar with this technique, and i am not, i am trying to learn?
That sort of is the whole critical point, leading with the feet
is leading your own body, but not the body of your partner.
Often that lead then comes from the arms - or a frame -
not really by means of an embrace but by a hold.
I do think you are over-thinking again although
I realise that in these times it is tempting.
Isn't that step projection in the sense opendoor uses just described differently with a different emphasis? the leader leading/projecting the followers leg using the torso, and the followers leg following the leaders chest by moving where it is needed based on the lead? The standard "the leader marks, the follower steps, the leader follows".
This "standard" is guilty of muddying the tango waters.
No, it isn't step projection as opendoor describes.
Step projection is about big visual movement
for appearance.
It is the opposite of social tango where movement
was/is movement of two bodies as one, bodies move
and legs follow to where they are needed for the next
axis (a regularly used tango term).
Do compare videos of Ricardo Vidort (delayed free leg
which lands under arriving body weight) with Jorge Dipari,
he of so-called Villa Urquiza, or today also known as Salon
both of which are really incorrect. Dispari takes long heel-led
steps and has toned arms which augment a weaker chest
connection and sometimes replace it.
(the main difference seems to be as usual that close embrace language emphasize the freedom of the follower, while nuevo emphasizes how the leader controls everything)
While I disagree with the detailed terminology,
I think you might have these the wrong way round!