Apple has always taken the position that it should not be possible for an app to be launched without the user approving it, so at present there just doesn’t seem to be anyway to do this the way you can do on an android device.
However, there are three different ways to do it using physical manipulation. It’s a little goofy, and you would have to buy an additional device or even two , but it can be done.
First, the simplest, although not the cheapest, is simply to buy one of the tiny actuators that are essentially a robot finger which can push the home button. Naran has the microbot push which has an optional rubber tip specifically for use on tablets and phones. It has its own IFTTT channel. I use these in my own home. The main problem is the cost: about $40 for Microbot plus another $90 for the bridge which is required for the integration. But it does helps of some of those “last mile” use cases where you just need to emulate a button push. But probably too expensive for most people.
The second is to take advantage of The magnetic case wake option on an iPad. You just have to add an actuator which can pull the case open and then let it drop closed again. This can look cool or clunky depending on your execution. But again, it should work.
The third option only works on the iphone, not the tablet. It has a “raise to wake” feature which means all you have to do is tilt the phone slightly and it will awake and stay awake even when it drops back flat for a brief time. So again, just a tiny actuator will do it.
In all three cases, you need something to trigger the device that will touch the phone, so you could use it different motion sensor for that.
The motion sensor detects motion, it triggers the actuator to move the tablet or tablet cover, the iPad wakes up.
Of all of these, I think the push microbot is the best looking. And also the simplest to set up. But it will cost about $140 just for one. And $50 for each additional one after that (since you don’t have to also buy another bridge; each bridge can support about 40 microbots)
So my guess is most people won’t want to do any of these, but I did just want to mention them. 