is this "need for my business model" or "need because we can't send a package without your address"?
Other than those two I don't see how spying on users is a business necessity.
Fairly typically applies to small local news websites in the US.
I was imagining a scenario similar to what Facebook is doing in Canada, with messages stating "We cant show you [x] because your government hates free speech" (hyperbole)
https://gdpr.eu/gdpr-consent-requirements/
Consent must be "freely given", which means you have not cornered the user into agreeing to you using their data. Requiring consent to data processing therefor excludes consent. You need to be able to say no.
The legal problem with geo-blocking to work around the GDPR is that the error page is usually not GDPR-compliant either. That said for most US sites which apply geo-blocking this is very much a "we'd rather lose that part of the audience than respect anyone's rights" kind of deal. You can roll out the GDPR-compliant treatment for your US users too and it'll be to their benefit. It just means your broken business model that relies on abusing your users' privacy might no longer work.
Note that there are EU sites that do force tracking ads on their users while still being GDPR-compliant by only doing so after the user has consented to it and offering a paid subscription without these ads as an alternative. So it's not just "but we need ads" but explicitly "but we want to harvest your data and do who knows what with it".