The developers of Little Snitch have confirmed that, at the very least, network filtering would work in userspace via the new Network Extension framework: https

The developers of Little Snitch have confirmed that, at the very least, network filtering would work in userspace via the new Network Extension framework: https://news.ycombinator.com/item?id=22677849 https://news.ycombinator.com/item?id=22677849 Marco Arment suggests that it's possible that Turbo Boost Switcher might not: https://marco.org/2020/01/13/macos-low-power-mode-redux https://marco.org/2020/01/13/macos-low-power-mode-redux