Many devices nowadays use Linux internally and if the development team was too ignorant to change the default, it'll behave like a web server and wait for wifi

Many devices nowadays use Linux internally and if the development team was too ignorant to change the default, it'll behave like a web server and wait for wifi to connect, then wait for the NTP time synchronization, and only then continue booting to userland. So yes, you can probably shave off 3 seconds of boot time by never connecting your gadget to the internet.