Connection GPIO interfaces in a imx6ul device takes around 18 seconds:
test@localhost:~$ time snap connect device-configuration:gpio device:gpio-85 real 0m18.196s user 0m1.130s sys 0m0.630s test@localhost:~$ time snap connect device-configuration:gpio device:gpio-86 real 0m17.135s user 0m1.030s sys 0m0.630s
It is very common for snaps that need to access GPIO to need access to tens of them. This implies that installation times for such snaps can take minutes. It should not really take that much time to create these connections.