How do I add a part function to an activation group?

Vizzy can do this
.
If active group (number) is true
Set part (number) to true
Otherwise set part (number) to false
.
Something like that

No

Do I need to unlock some tech for that?

When you click on the part, it should be in the very top drop down tab that activation groups are assigned. By default it will be set to “none” but should be a couple of selector arrows (one in either side) too cycle through which activation group you want it assigned!