Working abroad with a domestic job

I've been working remotely for almost 18 years without issue. Travel is an important part of my life and my mental health, so ever since restrictions lifted last year, I travel at least every other month (usually in the US, but this year I've already taken 2 int'l trips with another one planned for Fall.) I want to spend more time outside of the US, but not just for a quick vacation (think a month or 2 here & there--longer than PTO would allow).

Some employment laws affect whether you can physically work outside of your country, but I'm not moving out of the US permanently (yet). Ideally, I'd want to work from outside the US for 3-6 months a year total, but within my same time zone (mostly in Latin America & South America in places with good WiFi & infrastructure). (The company I contract for currently is clear that we cannot take their Macbooks outside of the US for security reasons.)

I'm now being considered for a FTE role with a new company. My Q is, should I ask about working outside the country during the interview process, or wait until someone makes an offer?

I think depending on how important spending time outside the US is for you, it might be better to ask about their policies earlier in the process. Since remote work has become more prevalent, many companies are changing their policies too with some letting their employees work up to 90days outside of the US (like Airbnb). At the same time, many countries are also working to make it easier for remote employees to work internationally. Brazil for example just created a "digital nomad" visa which allows remote employees to live in the country for up to a year (with the possibility for renewal at the end of the year.) With all these changes over the last few years, I don't think it hurts to ask.