Step 1: What is the highest level of spell you can cast?
Step 2: Subtract one from that. That's the highest level of Eldritch Secret spell you can know.
So yes, at character level 2 if you take this you can only select a technomancer or mystic 0-level cantrip, because 1st level spells are the highest you can regularly cast. When you hit character level 4 you can trade out your cantrip for a 1st level spell from the other list.
You may want to consider the Magic Academy Student archetype intead. It does the same thing but better, because you can spend ten minutes and 1 RP to change the spell known (or a regular Witchwarper spell known) to do cool utility stuff outside combat or be able to do things like condition removal/healing without investing spells known.