As a non-American working (legally) for a while in America (in Silicon Valley), I ran into a situation where my visa lapsed and I wasn't sure where I stood legally (like I wasn't sure if I was even allowed to be in the country any more). I can't remember how I found a lawyer. Anyway, I did a 15-minute consult over the phone. Actually, he was really casual about payment, at the end he said "mail a cheque to my secretary" and hung up, haha. Probably was mostly treating the call as a loss leader.

Anyway, among other things, he said that doing any work inside US borders, if not on a work visa, is technically illegal. Like apparently if I'm on vacation in the US, and I pull out my phone to answer a few work emails, that's technically a visa violation, not that in that case anyone's gonna mind. IANAL TINLA. And of course you're interesting in jurisdictions other than the US.

So, yeah, I think the way to find out is find a lawyer in the jurisdiction you'd be wanting to work from, one who advertises themselves as specializing in visa issues.