What you are looking for is a "Bed shaker". These are often used by the deaf to wake up. A relatively cheap phone-connected one can be found here but it's iphone only. This one works with Android. Both use proprietary apps. The website linked was just at the top of a Google search, you can find stuff like this on Amazon as well.

Isn't a phone technically a vibrating alarm clock?

How about a smart watch? I realise this is kind of specific but I have a Pixel 8 phone and a Pixel Watch 2. The alarms sync, and the vibration on my watch is enough to wake me up.

Might be kind of difficult to get to sleep with that inside you...

Unless that's what you're into I guess...

( ͡° ͜ʖ ͡°)

Use a Hitachi Magic Wand and an outlet timer.

Why does it need to sync with your phone?

What's the goal of connecting it?

As others have mentioned, I'd look for alarm clocks for deaf people. Many are in the $20 range but don't do Bluetooth.

that is one way to wake up

smart watch?

I use a Fitbit flex 2 for that purpose. I doubt they make that model anymore, but probably make something similar. The flex 2 is just a little lozenge-shaped thing that tracks movement, can vibrate, and has a few little lights. The app let's you set alarms (you turn it off by tapping it). I also have mine set to vibrate when I get a text message or a phone call in case I'm someplace noisy and don't hear it.

Try a Mi Band. I usually don't recommend Xiaomi products because of their heavy tracking and intrusiveness, but if you only use the band during sleep, you should be fine. If you already have the know-how (which I suspect you do), you can control it yourself through Bluetooth, and the band will erase all data it holds once transmitted.

You can get alarms that you place under the mattress and they shake the entire bed

Well my samsung galaxy phone and my samsumg galaxy watch are in sync

My Garmin watch alarm vibrates. It syncs with my phone but I don't know if alarms can be set from phone.

Just use a Japanese Train Conductor Bed that automatically makes you sit up!

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

https://www.amazon.com/iLuv-SmartShaker-Vibration-Bluetooth-Notification/dp/B08V6KH3SJ

This says it's bluetooth with android and apple but I don't know what the bluetooth connection syncs...

This is a stupid answer, but you could buy a cheap android phone. The carrier-locked phones are very inexpensive.

Bed shaking devices/deaf alarm clocks

What's the issue with just using a real vibrator? Probably easy to find and cheap.

I'd suggest these vibrating pads 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

I've seen vibrating dildos that look like carrots or cucumbers. They don't look like vibrators and if you're not into butt play, they certainly would wake you up in the morning.

Do you have the option to go to bed early enough that you can just wake up at the desired time without an alarm? May not work effectively till you’ve recovered sleep debt. You may need to sleep in late a few weekends to recover sleep debt, but don’t get carried away such that you can’t sleep that night. It also helps to tire yourself out with exercise so you can sleep when you want and then wake up without an alarm.

For other options, try a programmable butt plug maybe