Yes—that is hot glue, holding the home button bracket to the front panel. Good luck transferring that to your replacement glass. (Which you're going to have to do, to keep the Touch ID functionality after a cracked screen repair.)
Looks like the cable is a bit of a nightmare all by itself.
No surprises here: Touch ID in the Mini is powered by an NXP Semiconductors 8416A1 Touch ID Sensor.