I know that one thing I don't like about https://weworkremotely.com is that many of the listed jobs are not truly remote (they are limited to one country). At least on this board I can filter those out.
I think the term "transnational" would fit what you are describing better than the term "truly remote." The US is a very large place. Someone working for an SF startup from their Florida home is just as "truly remote" as someone working from Mexico, Canada, etc.