Look at it this way,
@Grumps - the 2004 Steel Challenge was won by an airsoft shooter from Japan (
https://en.wikipedia.org/wiki/Tatsuya_Sakai_(marksman) ), and the field he played against wasn't exactly no-names, either.
And yes, this is a T.Rex Arms video, but the validity of the idea doesn't really depend on which YouTube Channel it's hosted on....
Sub-caliber training has always been a thing, be it .22LR - or airgun (and in the last 20 or so years, airsoft). But it does have its limitations.
With the .22LR, the biggest difference will come from recoil and muzzle blast. This should come as no surprise, as a lot of experienced shooters prefer to start novice shooters with .22LR for this very reason. Back in the shortage/craze at the beginning of the last decade, things got so bad that we saw even high-end training schools allowing students to shoot .22LR in place of centerfire defensive/duty calibers. Towards the end, even Larry Vickers allowed the use of .22LR in his classes (although he discouraged their use:
overall, simply realize that every instructor has his/her own beliefs, which are based on their personal experiences: Vogel places high value on dry-fire, and even continues to press the trigger to simulate follow-up shots after the striker has released - but he says that airsoft is of virtually no value; Hackathorn believes that dry-fire is really of higher benefit to novices and beginners; etc. ).
Also, unless you are using the same fire-controls, you won't get 1:1 benefit in terms of the specifics of that trigger path. That said, a trigger path is a trigger path, and practicing towards the perfection of executing
the trigger path will benefit any shooter. This can also be said of other marksmanship fundamentals, even if there's some differences between the sub- to full-caliber platforms.
Note that depending on the specifics, some .22LR (or even airsoft) "training guns" will not operate in completely the same way as their full-caliber counterparts.