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’d suggest these vibrating pads or pagers you get at some restaurants (you can pick up your order when the thing goes off). They’re crazy loud. Probably still loud if you put them under your pillow.
Kinda like this: https://www.alibaba.com/product-detail/JT-9303-OEM-Waterproof-Wireless-Transmitter_1600599278778.html?s=p&spm=a2706.7843667.0.0.66d34356eKubIC