If you do a full game run without a timer, it could be verified?

yes, you do not require an on screen timer, though please keep in mind we are currently dealing with a long run in queue so it might take a while to be verified

Yes, your run can still be verified if you do not have a timer on the screen. The mods will use external timers to verify that your submitted time is correct, and they will alter it if there is a difference.