Depending on where you are going on vacation, you may have a measure of control over what you will be eating. For Keto dieters who are staying at a hotel and will be traveling from tourist spot to tourist spot, check with your hotel and see what kind of meal options their restaurant offers or whether there’s a continental breakfast. There may be fewer Keto-friendly options to choose from, but you will likely be able to find something to enjoy. Also, when out traveling, be sure to stop at grocery stores and purchase some Keto-friendly snacks that travel well, such as cured meats or cheeses, which can help keep you from overindulging.
As for alternatives you might consider Argentina, where of course it will be late spring in November. Buenos Aires is a wonderful city and recently they’ve been going through a financial meltdown again so their currency has dropped a lot, making things unusually cheap again. You could spend 3 or 4 days in Buenos Aires and the rest in the Mendoza wine country or Iguazu Falls or Bariloche for some adventure. From everything I have heard it’s all safe and civil there, so it’s just a matter of the local currency going down in value.
If you are looking for first-rate destinations that are among the cheaper European cities, I’ll suggest Prague, Budapest, Krakow, and Berlin. You could visit all four of them by taking trains, or choose any one, two, or three. In December you can get quite a nice room in any of those cities, with Berlin being the most expensive by a bit. Food and attractions are also quite affordable in those cities.
Otherwise the big draws are the Great Barrier Reef, which is obviously focused on diving, snorkeling, and water activities, so it may not be too interesting, and Uluru, which is the big rock in the center of the country (and not near anything else of interest). There is also wine regions in the south near Sydney, and of course nature parks to see kangaroos and the other indigenous animals.