A doorway is an excellent and fitting feature to include in your virtual teaching space. If the door-frame contains a door, it should be open. It is often tempting to keep all doors that are in view closed, to shut out the rest of your home and life. But consider the symbolic significance of a closed door and compare it to that of an open one.
An open door invites curiosity and sets up an atmosphere of questions, mystery, and adventures; of transformative enquiry, seeking knowledge, and opening minds. Your doorway enhances the “higher education” feel of your learning space. (To which you are yourself also a doorway.)
An open doorway’s quintessential defining characteristics: liminal zone, portal to other unknown worlds, and between them a movable barrier. Even just slightly open, your audience can glimpse what lies beyond, and as the door is clearly unlocked they can see that it’s not an immovable or impenetrable impediment—like a wall—but one that can be moved to open it further and access what’s beyond. That is: they will have to exercise decision, will, and effort to push that door further open first. (You can of course lend a hand, as needed, from the other side if the door sticks or a student needs more help.)
A door might already be fully open, or it might have been removed entirely, or never have been in the frame at all; visibly, anyway. Your audience will next have to exercise decision, will, and effort so as to make their way across the doorstep. No-one can step inside for them. (Again, depending on the situation and student, you could help; mindful that if you pull someone forcefully, they might trip and fall.)
Doorways are more than doors as they’re also ways: about what’s beyond them, about their pathways, and about finding paths and ways of knowing. (The latter and its self-knowledge might also be part of the knowledge, and indeed the highest knowledge, to which you can guide students in higher education.)