All the vibrating alarm clocks I could find do not sync with your phone, and have to be set manually. I thought about getting an Arduino, but then I will have to build the whole thing by myself. The only logical conclusion I could come up with is to get a programable vibrator. But most of them are either very expensive of look too much like a vibrator (sus).
This is the closest I got: https://www.amazon.com/dp/B09NNFPHXG https://www.amazon.com/dp/B0CD7FPFQ5?th=1
I used to use this, you can turn the audible alarm all the way off and just use the shaker!
https://www.amazon.com/Sonic-Alert-SBB500SS-Extra-Loud-Flashing/dp/B000OOWZUK
I had one of these until I got married. You will wake up, many times in a panic. Good times.