I have the same issue. Europe is my main market and Zoom Events is restricted to just 12 of the 44 countries in Europe. So i accept registration payments off the Zoom platform for just those outside Zoom's regions (i have a separate page on my website) and then upload each as a pre-registered attendee on receipt of payment. Important...when you pre-register them, make sure you select "No" to "Do you want this guest to register for the event" (see attached). Otherwise, they will face the same problem and be blocked when they enter registration data.
In my case, most attendees are within Zoom's regions so it is only an occasional issue. But if a large number of yours are outside Zoom's regions, you may want to do ALL registration off site as the downside of my work-around is that I don't collect registration data on those I pre-register and many end up emailing when they initially start registering with Zoom and encounter the geo-block.
I have a test site running concurrently with my live event so i can experiment as issues like this arise. As with all things in Zoom Events, test, test, test before you implement. Good luck.