I needed to help a friend on a remote computer recently. A coworker told me about Chrome Remote Desktop, which works on any computer that has a Chrome browser, including Linux, Mac, Windows, iPhone and Android.
Chrome Remote Desktop is an easy-to-install plugin for Chrome, and is gratis (no cost). It worked quite well, and I’m happy to recommend it.
Alternatives include copilot.com, which is free on weekends. Lifehacker has a list of solutions as well.