Mac is boot looping after Mojave update. Can access disk utility. No backup. Can I get the data off it?
Reset the SMC (hold opt control shift and the power button for 20 seconds) then reset the NVRAM 3 times (3 on and off of the lcd monitors backlight) first.

Try to boot into Recovery mode or Internet Recovery (option command and R keys).

Is it looping after the Apple logo has come on the screen? If so then you probably can do what you mention since in that case it's likely a software issue although the drive could be failing. Do you mean the update failed and then the OS wouldn't boot right after?