Simple timers for Christmas lights mostly do not include three pronged plugins,, just a heads up,, tho I bot a cpl of 'cheaper' timers for the lights this year that were three pronged
good catch.
i've never seen a two-prong digital timer. i'm sure they are out there.
also if you run hid i'd never recommend a digital timer. i'd stick with mechanical. most hid will need heavier wiring as well.