I've just glued a rucksack and trainer insoles back together with this stuff:
https://bond-it.co.uk/adhesives/contact-adhesive/The rucksack seams/glue had perished and this stuff has saved it from the bin.
I bought a 250ml can which comes with an integral brush.
It seems to work very well. Best to apply it outdoors though as it's pretty potent. It's fine once dry and seems to remain flexible and holding the material I've used it on together nicely.
I've not tried on Goretex but can't see why it wouldn't work.
There's also seam seal that's marketed for outdoors kit.