More and more clubs are offering remote testing service. It is not “online testing” and there is no such thing as “walk-in” (no appointment needed) testing. You’ll be taking the exam while being monitored live via video conferencing software, which means you need access to, at a minimum, a computer, webcam, microphone, and fast internet connection.
Procedures are evolving by the week, so going into more detail at this time would be pointless. I suggest you check out this link for more information and to find a group offering remote testing.
Kudos to the folks at HamStudy.org for developing software to expedite the remote testing process!