How about this one - slow below best glide speed to steepen the approach angle!?
No.
My "no" is supported by the fact that this is not an approved training nor operational procedure anywhere. And, as correctly mentioned, it puts the plane is a regime of flight where it will be necessary to accelerate it before it can be safely flared for a landing. Doing this would be similarly unsafe as a prolonged climb at Vx, where there is no obstacle to clear. If the engine stops, you have to just up precious altitude gliding to accelerate to best glide speed (or probably a little faster) so you can successfully flare to arrest your rate of descent. Speed is safety!
A review of the concept of a "height/velocity" or "Avoid" curve for a helicopter, and how that actually applies to an airplane as well will support this understanding.