We have to make sure we're defining our terms precisely here. Libertarians oppose non-voluntary interactions, which includes pretty much all taxes.

There's no objection to opting in to a community that has fees for services that would look like taxes to any normal person, but would be considered meaningfully different to a libertarian.

Form of government is considered relevant to some (probably most) libertarians, but I don't see the relevance from a fundamental principles perspective. They're all systems where a group of people are regularly violating the rights of others.