I agree that it would not be common to find.
A place that caters to race cars would have them, or you could get recommendations from a shop that works on race cars. Real race cars, not fancy cars for the street.
(caution, below is long explanation where it's very common to shave tires)
I used to race competitively in a past life. Sometimes when buying tires, we could choose how much tread depth we wanted. The less tread depth, the better response when you turning the steering wheel. It's also helps more accurately place the car when taking turns.
Think of a tall soft eraser that you pushed down onto a table.
If you twist the end your holding, there's delay for the bottom to follow.
Now imagine the table was super sticky, and you tried to twist the eraser.
It's easy to see that you have to twist your end more,
to get the bottom, touching the sticky table, to rotate and follow your twist..
With stick race tires, that's the case. Really sticky race tires can be shaved to give a quicker response to your steering input.
Ideally, you want no tread for race tires. Grooves are only to make them borderline street legal for the road
or for rain.
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A shop offering shaving for race tires ->
https://philstireservice.com/shop/toyo-proxes-rr/
and a regular tire shop talking about shaving for street tires, for the purposes describe earlier.
->
https://blog.tireamerica.com/2018/04/12/what-is-tire-shaving/
