Yeah, the lunge technique bypasses the hardest part of the move.
Both of my legs are equally capable–there does not appear to be a strong side.
I actually did this basic move as a strength exercise for cross-country (many years ago). I just found out now that they are called pistol squats.
OK, I have a new fitness goal now.
At almost 85 Y.O., it takes me both legs, one arm on a nearby chair seat, and the other arm grasping a cane. Then, after much grunting, verticallity can be slowly obtained.
Getting old ain’t for wimps!
I can’t figure out how to get my body thrown forward enough to get my weight on my legs, let alone only on one. And getting one leg under my body would require resting on my other leg.
That said, I tried it from just a chair, where my legs would already be under me. I don’t have the balance for it–so my other leg automatically hits the ground to keep me from falling.
OK, I can do a couple of those (they’re hard) but I wouldn’t call that “sitting on the floor.”
Those were the exercises I did when I was younger. Getting up from sitting on the floor uses the same form, but it starts from slightly lower.
I’m a klutz, so even though I have the leg strength, I have to say no.
Yes, I can do this easily which ain’t bad at all for being at the half century mark.
With the caveat that at the end of a long, hard day not so much but presuming I am normally rested, yes, I can do that.
Balancing is the hardest part, though for some people lack of strength or flexibility (both of which are required) might also be an issue.
What I can’t do is squat or kneel for an extended period without agonizing knees, so I’m much more inclined to sit on the ground and get up from there rather than avoid the sitting-down-getting-up thing. I’m presuming my practice at getting up and down from the ground has something to do with my still be able to perform the maneuver.
I do expect that at some point in my old age this will be beyond me, but I’m trying to put that off as long as possible.
Or, if you had spent the previous day doing dozens of them when trying out different positions and methods. In that case, you might find that they are nigh impossible to do without something holding onto something. 
Sitting from buttocks on the ground? No.
Sitting from buttocks resting on one foot and able to hold onto the other foot with my hands? Yes. Not easliy but not too hard either.
True pistol squat leg straight out all the way down? Not quite, I think a flexiblity deficit there.
Which do I answer?
Almost to that state. I can get up, just barely, using both legs and both arms. It really helps to have something to grab, but I can do without it. I’m 77, 78 in January.
Truly using only ONE leg and no hands or the other leg in any way and from my butt? No.
Introducing just a hand or the ability to momentarily put my other knee down? Yes.