[quesera]

The second in series would not be powered continuously, so it would only work for the first cycle.

You'd need to separate the timer power from the switched power. Easy to do, but not how the cheap ones work.

Also, the settings are not precise enough to get a repeatable interval across two devices.

On the other hand, it's a very simple DIY electronics project. Arduino is extreme overkill, but will also work.