I mean few drops of hot water from kettle on freshly grounded tampered coffee puck wouldn't serve as preinfusion alternative?
I don't see any difference with machine preinfusion and I don't think it needs to be done under pressure, or it must?

Coz my machine don't have that function and this way it would be manually controlled amount & temperature and then few seconds later inserting portafilter into the machine and go full blast extraction....
Of course would attempt not to damage the puck ....
Anyone tried it?

The current term for similar practices is "pre-wetting."

In my limited experience - with a Silvia - it definitely does not give the same taste as pre-infusion (which is really infusion at a lower pressure than the following (brew) pressure and greater than atmospheric pressure). I gave up, but people should experiment with their own taste buds and decide for themselves.

I have read that extraction yield does go up, although I did not test this, and wonder about confounding factors. To simplify, you can try wetting the puck in the portafilter with a WDT spray bottle. IIRC, people found that temperature of the sprayed water (within reason) did not make a noticeable difference (in extraction yield).

Not sure if I am right but the way I see pre infusion is to completely soak entire puck under low pressure so that the integrity of the puck is not compromised. This results in less channeling and more even extractions from my experience.

When I got my GS3 MP a couple of years ago, I moved the switch location to allow for pre-wetting of the puck. I found that even after thirty seconds or so of zero pressure dribbling, the water had only penetrated at most the top third of the puck.
While it might help slightly with puck integrity (I don't recall whether it did or not), it mostly just muddied the flavours in the cup.

Seems like more of a blooming technique, with similar results though. Preinfusion usually involves pressure, with a minimum of boiler pressure and increasing from there by machine or technique.