Even ones with an adjustable dial are too rough? First off I’m sorry you have nerve damage that sucks second off. I hope the hand dildo works.

I use an intimate vibrator on my face occasionally to loose up my sinuses. Just give it a good wash before and after; there's nothing wrong with it.

what about, like, a regular-ass electric toothbrush?

I use my vibrator on my neck sometimes when I have a migraine, it works really well.

I advise not to go "cheap" and make sure you get something body safe. (Cheap toys could be made with harmful materials.) Honestly if you go to a sex shop and explain what the need is, they'll be more than happy to guide you to toys that have the vibrations you need. There's buzzy or rumbly types and come in a huge range of strengths and textures

Seriously, they'd be ecstatic to help! And you would absolutely not be the only one

Unsolicited recommendation?:
I'm not sure what you need specifically, but something like this might work? https://lovecrave.com/products/vesper It's small and you can use the tip for pinpoint or the length of it for a larger area. It is rumbly, surprisingly so for such a small device, and has different strengths (and patterns), and doesn't look like a sex toy

Get a We-Vibe Touch! It’s got a silicone exterior and it goes from little vibrations to fairly strong.