I've used hundreds of cans of expanding foam in my life, and also used the "2 part, stubby gas cylinder" type systems that mix in the nozzle and eject a urethane spray..

The foam produced by the latter is fantastic, far better in terms of structure and fill than regular expanding foam, but it's a bit intense to use; you typically do all your prep and then do the foaming in one go because the nozzle is essentially ruined 10 minutes after you stop using it.
i've an application that would be better done as a bit more of a stop-start affair - i really want 2 part performance for but I don't want to mess around with the liquid variant, nor do I really want to use a 2 part cylinder kit..

However, I see a few kits from brands like Penosil for what appears to be a foam spray like what a 2 part system would emit, but in a single 750ml can format like regular expanding foam. The shiny ad brochures and pictures make it look like a 2 part system result, in that the foam is depicted as leaving the nozzle at high speed and fanning out but close inspection of the gun and cans don't draw any signifcant and obvious difference to the typical gun expanding foam I'm used to that is used at lower velocity with the gun nozzle "laying" the foam like a cream piping bag, rather than spraying the foam. The more I look at it the more it seems that this is just like regular expanding foam with a plastc clip on the nozzle end to fan out the spray, though perhaps the formulation in a Penosil can differs to that of a typical Soudal Soudafoam fan

Has anyone used these 750ml can kits and alo the 2 part gas cylinder kit? How do the two of them compare? What is the structure and adhesion of the finished foam result of a spray can?

The application is to fit kingspan insulation with small gaps and then spray foam to the back of the gap so it bonds to the wall and expands into the void, notionally turning the wall to a single sheet of kingspan. I would butt them up but the board edges are a bit misshapen in areas and I've had good experience with the 2 part system used in a similar way with gaps to spray the foam down, as it adheres to the wall, and seals all in one go

Yes, I've never found the plastic nozzle extensions satisfactory because, judging by the gun construction, the PU+solvent is under can pressure all the way to the brass tip of the gun whereupon it bursts forth and foams up. Putting the plastic straw on it collapses the foam again and it never expands well after it emerges from the free end of the straw

A gun with a long bendy metal straw nozzle was similarly afflicted; I set it aside after one use and it became spare parts for my regular gun.

This is a promo video for the penosil:
https://www.youtube.com/watch?v=feuDTk-UDp0&t=121s

It looks like regular expanding foam but the can lid is actually a snap-off spray nozzle that you stick on the end of your regular gun in place of a plastic straw.. Color wise, the foam in the penosil can doesn't seem to be significantly different to a bog standard soudal/no nonsense/everbuild type, which made me wonder "would this plastic nozzle work with soudafoam at half the price?"..