A hidden threat in this, is that podcasting can look like journalism to many economies. If you "report" on current affairs in any way, you can fall into the trap. Mainstream broadcasters are always super-careful when staff are sent to the USA, to get the right visa. If the staffer just goes to the USA, they have to make damn sure they don't return to work, even if they take that call about some story, there is a risk…
I always thought that a "tourist" visa allows you to do "work" for your non-US company, it just prevents you to from "working" for a US company, or being paid by a US company for work done during your visit. I entered the US dozens of times on an ESTA for work reasons, I always declare I'm there for "business", offering detail if needed, and never had any issue.
For example, in the US case, check out https://en.wikipedia.org/wiki/B_visa#Acceptable_and_prohibit.... The rules for B visas apply to ESTA as well. Journalism is explicitly prohibited on B visas.
This is why my employer's internal immigration processes, even for short-term visits like conferences or whatever, present you with a comprehensive list of different categories of activity you might be undertaking to determine whether you need a work permit or not. It's annoying, and our internal immigration systems are very, very much imperfect, but I can see how it came to be.