We wonder if there is a way we can test the behavior of a Power-Up on personal boards, without publishing untested changes to the “live” Power-Up first. So far, we use a custom Power-Up for development and testing, but those seem to be always bound to a team and are not available on personal boards.
There is not a way to test a Power-Up on a personal board. All Power-Ups are tied to an owning organization and, until made public, can only be enabled on a board within that team.