According to this, as of 2022, in the US, only 175k households were still using dial-up Internet service from any provider. That’s not a lot of people.

reviews.org/…/how-many-us-households-are-without-…

Around 175,522 households use dial-up internet at home.

I’m guessing that many of those realistically have other landline options and just haven’t switched.

kagis

The amusingly-named-given-the-context dslextreme.com apparently continues to offer nationwide dial-up service.

www.dslextreme.com/dialup/residential