I teach the Planche Lean as follows:
Assume front straight arm plank/prone/pushup position. Lean to desired angle, then Hold.
So it is a hold. The entry to an from the hold do not count as part of the time. However, you could use it as such since it would be under tension. Thus TUT. Or it could be considered an "Embedded" Progression from BtGB.
I have generally always just substituted PlancheLean for whatever shape planche progression.
To note, if you cannot do a Planche Lean of significant angle (at least equal to the required angle for a tuck planche), I do not find it very useful for such trainees. Sometimes, those trainees are weak/not strong to the point that they should merely work ring support or L-sit (on rings) or floor or PB instead.
If they cannot hold a proper RTO ring support (for say 30s at least), they should not move on to Ring L-sit since the Ring L-sit will probably be improperly done: hunched over chest, shoulders not pushed down, hips too far back, rings turned in.
Usually in my WU, we do Inchworm walks where you start in a pike stand with hands on floor and legs straight (how close your hands are to your feet depend on pike flexibility which is ok) and then walk out to the straight arm plank, planche lean, then pushup or pike hips and walk feet toward hands.
Repeat for 20-40'. (Distance across floor).
Personally, I find it useful to just get my wrists warmed up.
Some people will planche lean till they faceplant, but this is not my preferred method. This is where I would do the pushup but some others may simply pike the hips and walk the feet toward the hands.
Besides, mature females will not enjoy this when faceplanting; and others, while it is comical, it isn't very useful to yourself though it is amusing to others.