Gorrila glue is fantastic. Yes it expands if uncontrolled. If some oozs out of a joint, wipe it off before it hardens, however if the wood being contacted is protected by a covering, the resulting loose hole hardened foam is not a problem.
: I've used it for laminating bows with maple on maple and hickory on maple and they are still shooting after 20 years.
: Most of the poly glues are about the same, I think, as I've used LePages with similar if not exactly the same results. It will expand into any crack, crevise or whatever it can find, but the lightly expanded foam has little strength. A hard compression of it into a crack will certainly seal that open crack, though. A dead-end crack that does not go through all the way can be repaired with this type of glue just as any other. Let the poly glue start expand into the crack as its starts to cure, then clamp and allow to finish curing. The harder the glue is clamped (to a degree), it seems the better the bond. Wood glued to wood (clamped) will split if stressed enough but never breaks on the glue line. Do not clamp hard enough to press out all the glue - same as any wood glue, but it can be clamped harder than most wood glues. Wet one surface for a faster cure. It requires moisture to 'kick' it off and will draw moisture from the air for this. Around here (mostly low humidity) it requires water to help it. Unlike wood glue, poly glues don't dry, they cure. It is sticky,strong glue.